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REPORT

OF THE

SECOND RESEARCH CO-ORDINATION MEETING

OF THE

FAO/IAEA CO-ORDINATED RESEARCH PROJECT

(D1.20.06)

ON

MANAGEMENT OF NUTRIENTS AND WATER IN RAINFED ARID AND SEMI-ARID AREAS FOR INCREASING CROP PRODUCTION

6 - 10 March 2000 Tunis, Tunisia

Fa'4- - ` ~I~iMlkicr _. _

Prepared by: P. Moutonnet, Scientific Secretary, Soil and Water Management & Crop Nutrition Section, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture

CONTENTS 1. Introduction..........................................................................................................................1 2. The Co-ordinated Research Project .....................................................................................2 3. Objectives of the Meeting....................................................................................................2 4. The Meeting.........................................................................................................................3 5. Conclusions and Recommendations ....................................................................................4 6. Acknowledgements..............................................................................................................4 7. Key References....................................................................................................................5 Annex 1: List of Participants.....................................................................................................7 Annex 2: Programme of the Research Co-ordination Meeting.................................................9 Annex 3: Summaries of Presentations ....................................................................................13 Annex 4: Models and Minimum Data Sets .............................................................................27

1. Introduction

For the two last decades, the improvement in food production can be attributed largely to the introduction of high input farming, involving new crop varieties grown on fertile soils and well supplied with irrigation water, fertiliser, and pesticides. However, 84% of arable land used world-wide for agricultural production is non-irrigated. Due to increased pressures from growing populations, a yield increase in the semi-arid areas is urgently needed. In large parts of arid and semi-arid areas, the soils are of low fertility, and the per capita production is often declining. In fact, the economic cost of high-input agriculture prevents most subsistence farmers from adopting these techniques. Therefore, the arid and semi-arid areas have not benefited from the green revolution as much as regions well endowed with water resources. There, crop responses to inputs such as fertilisers are generally low and unprofitable to the farmer; the problem of increasing crop productivity in these regions is widely recognised as difficult.

Nevertheless, there is some evidence that crop yields in semi-arid regions can be profitably increased and the yield variation decreased with a combination of careful management and low inputs of nutrients. The key is to combine nutrient inputs with cropmanagement practices that increase the supply of water to the crop. The steps to optimise crop water use efficiency are known in principle: infiltration of rainfall into the rooting zone should be improved, water losses by soil evaporation and weeds should be reduced, and extraction of soil water by the crop should be maximised. The long-term sustainability of many existing farming systems in arid and semi-arid environments is questionable: removal of all outputs is leading to rapid depletion of soil organic matter and nutrients. If crop production can be increased and sustained, there are grounds for optimism about the problem of land degradation as additional crop production leads to larger quantities of residue.

Isotopes and nuclear techniques are very crucial in understanding how various factors influence beneficial effects of crop residues, nutrient release and plant nutrient demand, nutrient and water uptake by plants, and soil physical and moisture retention properties. The isotopes used were the following: '3C, 'SN and 32P. The soil moisture neutron probe is the most appropriate equipment that is used for monitoring sub-surface soil water content and establishing the water balance. Experiments involving "N-labelled fertilisers have been conducted for measuring N-fertiliser efficiency and the contribution of legumes to biological nitrogen fixation. The data gathered enable the recommendation of management practices that will enhance soil fertility build-up in different cropping systems that can take into consideration plant growth, soil nutrient release, and rainfall input. The large data set generated has begun to be incorporated into existing models.

A Consultants' Meeting on "Management of Nutrients and Water in Rainfed Arid and Semi-Arid Areas for Increasing Crop Production" was held in Vienna, Austria at the IAEA Headquarters from 26 to 29 May 1997. This Consultants' Meeting established the goals and

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objectives of the Co-ordinated Research Project (CRP), a programme that was initiated in cooperation with several International Agricultural Research Centres: ICRISAT, CIMMYT and ICARDA. The Joint FAO/IAEA Division, through the Soil and Water Management & Crop Nutrition Section, started the implementation of the CRP, targeting the following overall objectives:

• to investigate management strategies that optimise and sustain the productivity of rainfed farming systems by increasing the efficiency of water and nutrient utilization;

• to define appropriate technologies to enhance crop water use and nutrient uptake, and to ensure their applicability at the farm level;

• to test crop responses to water and nutrients in relation to crop sequence and surface management in field experiments using nuclear techniques;

• to promote collection of minimum sets of data in all experiments, storing the data in a common data base, testing and applying simulation models and using the data and models in training national staff.

Further recommendations on the implementation of this project can be found in the

IAEA-TECDOC-1026 published in July 1998.

A first Research Co-ordination Meeting (RCM) was held at IAEA Headquarters from 6 - 10 July 1998 in order to establish the objectives of the CRP: guidelines are included in the first report of this RCM.

The present report describes the objectives and the programme of the second RCM held in Tunis, Tunisia from 6 to 10 March 2000. Furthermore, conclusions and recommendations given for the implementation of the CRP are outlined here.

2. The Co-ordinated Research Project

This international networked research project is operated as a part of the IAEA Research

Contract Programme. As such, the FAO/IAEA CRP on "Management of nutrients and water in rainfed arid and semi-arid areas for increasing crop production" is composed of seventeen research teams, twelve of which are contract holders and five agreement holders. The Contract Holders were selected from applications received in 1998. The duration of the CRP is five years (1998-2002), with four RCMs planned to be held every eighteen months. Such meetings encourage close contact and provide a forum for information exchange between scientists and institutes involved.

3. Objectives of the Meeting

The objectives of the second RCM were as follows:

• to present results of experiments conducted on-station and on-farm during the

cropping season 1998-1999. • to reformulate guidelines for implementing the CRP. • to introduce new experiments to be carried out before the third RCM (2001).

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The meeting also included a scientific visit to INAT (Institut National Agronomique de Tunisie) and CNSTN (Centre National des Sciences et Techniques Nucleaires). 4. The Meeting

The meeting was attended by seventeen scientists from fourteen participating Member States, and a number of local scientists. Unfortunately, one agreement holder was not able to attend the RCM due to circumstances beyond his control. The list of participants is given in Annex 1.

The meeting was formally opened by Mr. Mougou Abdellaziz, Director of IRESA (Institution de Recherche et d'Enseignement Agricole), Mr. Moncef Harrabi, Director of INAT and Mr. Amouri, Local Representative of FAO. Mr. Abdelmajid Maajoub, Director of CNSTN and Mr. Mahmoud Baraket, Director of AREA (Agence Arabe de 1'Energie Atomique) also participated in the ceremony. They all welcomed the participants and informed them of the importance of CRPs and the objectives of the meeting. The programme prepared for the meeting was followed with some minor changes in the order/number of presentations (Annex 2). 4.1 Presentations

The reports of the participants covered a wide range of topics on cropping systems of arid and semi-arid areas. Rotations of cereals with fallow or food/forage legume crops, depending on location and rainfall, are well documented in West Asia - North Africa. In the next few years detailed data will continue to be taken, and interpretation made, especially with respect to findings on N and water dynamics in the rainfed cropping system. In Southern Africa, two water management techniques (tied ridges and cultivation) are being evaluated in combination with three nutrient management options. In China, the most effective management practices to increase crop yield could be the combined use of organic and manufactured fertilisers and improved varieties of crops. Excerpts from the presentations are given in Annex 3.

4.2 Scientific Visits

The third day of the meeting, 8 March 2000, was devoted to the following visits:

• INAT, where its Director welcomed us; later, with Prof. Mechergui, we paid a visit to his laboratory which was recently upgraded for the use of radioactive tracers. At present, 32P is used in association with researchers of the Ministry of Agriculture, Soils Directorate (Dr. A. Mtimet, counterpart of TC Project TUN/5/017).

• CNSTN, some distance outside of Tunis, where "Co irradiation facilities are being installed

for food preservation and other relevant activities, including isotope hydrology.

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On the return journey to Tunis, the group visited the site of Carthage under the guidance of the Museum Director. 4.3 Discussion Sessions

One day was devoted to discussions and formulation of recommendations to be made to participants. The contract holders were split into groups led by the agreement holders, and dealing with:

• editing abstracts for the present report; • establishing a database for DSSAT (Decision Support System for Agricultural

Transfer) with the assistance of Ms. Lee Heng; • running a simulation model, e.g. APSIM (Agricultural Production Simulation) with the

assistance of Dr. S. Asseng. 5. Conclusions and Recommendations

• The objectives of the meeting were successfully completed. • This second RCM confirmed the usefulness of the Consultants' Meeting and first RCM in

reviewing the current status and future trends of the application of nuclear techniques including neutron gauges in the management of nutrients and water in rainfed areas.

• Through the presented reports and related discussions, it was clear that the objectives of the CRP are quite relevant to increase crop production of rainfed areas through the improved management of nutrients and water.

• Simulation models have been evaluated (DSSAT, APSIM) for their respective potentials. Owing to the previous experience undergone with DSSAT in the framework of the "Irrigated Wheat" CRP, this model has been selected, and a minimum data set is provided in this report (Annex 4). On this basis, data will be collected; Dr. L. Heng (Soil Science Unit, Seibersdorf) will provide assistance in this activity.

• Plant samples will continue to be sent to the Scientific Secretary for atom %'SN excess and delta `3C measurements. Soils and liquid samples have, most of the time, to be treated locally (digestion, distillation, micro-diffusion) before being shipped to the IAEA. Please refer to documents distributed during the meeting.

• Whenever possible, participants of the CRP are encouraged to publish their results in scientific journals.

6. Acknowledgements

The author is grateful to all participants for their active involvement in the RCM. In

particular, thanks should be extended to Prof. Mechergui for the key role he played as local organiser of the RCM.

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7. Key References

F.L. Walley et al. (1999). Water-use efficiency and carbon isotopic composition in reduced tillage systems. Soil Sci. Soc. Am. J. 63:356-361. E.O. Leidi et al. (1999). Variation in carbon isotope discrimination and other traits related to drought tolerance in upland cotton cultivars under dryland conditions. Field Crops Res. 61:109-123. A. Arslan et al. (1999). Carbon isotope discrimination as an indicator of water-use efficiency of spring wheat as affected by salinity and gypsum addition. Commun. Soil Sci. Plant Anal. 30:2681-2693. B. Martinet al. (1988). Stable carbon isotope composition (8'3C), water-use efficiency and biomass productivity of Lycopersicon esculentum, Lycopersicon pennellii, and the F 1 hybrid. Plant Physiol. 88:213-217. C. Kirda et al. (1992). Carbon isotope discrimination at vegetative stage as an indicator of yield and water-use efficiency of spring wheat (Triticum turgidum L. var. durum). Plant and Soil 147:217-223. K. Winter et al. (1982). Effect of low relative humidity on 8'3C value in two C3 grasses and in Panicum milioides, a C3-C4 intermediate species. J. Exp. Bot. 33(132):88-91. W. Stephens et al. (1999). Modelling the benefits of soil water conservation using the PARCH model - a case study from a semi-arid region of Kenya. J. Arid Environ. 41:335-344.

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Annex 1

List of Participants Research Contract Holders

ARG-9985 JOR-9988 Dr. Daniel PRIETO Dr. Deifallah m.d. BADARNEH Instituto Nacional de Tecnologia Agropecuaria University of Jordan Estacion Experimental Agropecuaria Santiago Faculty of Agriculture del Estero Amman Water-Soil-Climate Division JORDAN Jujuy No. 850 Casilla de Correo 268 E-mail: badarneh@agr.ju.edu.jo 4200 Santiago del Estero Tel.: 962 65 355000, ext. 2515 ARGENTINA Fax: 962 65 355577 E-mail: dprieto@inta.gov.ar Tel.: 54 385 4224430/4730 KEN-10330 Fax: 54 385 4224596 Dr. Isaya Vincent SIJALI Kenya Agricultural Research Institute CPR-9986 National Agricultural Research Laboratories Dr. CAI Guixin Soil and Water Management Institute of Soil Science, Academia Sinica P.O. Box 14733 Department of Soil-Plant Nutrition Nairobi P.O. Box 821, 71 Beijing Road East KENYA Nanjing, Jiangsu Province 210008 Tel.: 254 2 444031 PEOPLE'S REPUBLIC OF CHINA Fax: 254 2 443376/443926/443956 E-mail: gxcai@ns.issas.ac.cn Tel.: 86 25 7713781 MOR-9989 Fax: 86 25 3353590 Dr. Khalil EL MEJAHED Institut National de la Recherche IND-10169 Agronomique Dr. Venkata Ramana MAPARLA Centre Aridoculture Acharya N.G. Ranga Agricultural University B.P. 589 Regional Agricultural Research Station Settat Palem, Mahabub Nagar District MOROCCO Andhra Pradesh 509 215 E-mail: inra@settanet.net.ma INDIA Tel.: 212 3403210/18 E-mail: J.Kumarrao@cgnet.com Fax: 212 3403209/3402626 Tel.: 91 08540 28646 Fax: 91 08540 28646 NER-10402 Dr. Issaka MAHAMAN IND-9987 Institut National de Recherche Agronomique Dr. Manbir Singh SACHDEV du Niger (INRAN) Nuclear Research Laboratory B.P. 429 Indian Agricultural Research Institute Niamey New Delhi 110 012 NIGER INDIA E-mail: intarna@intnet.ne E-mail: mssachdev@excite.com Tel.: 227 72 34 34 Tel.: 91 11 5711902 Fax: 227 72 21 44 Fax: 91 11 5711902

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PAK-9990 Research Agreement Holders Dr. M. Mohsin IQBAL Nuclear Institute for Food and Agriculture AUL-28697 (NIFA) Dr. Senthold ASSENG Nuclear Agriculture Division CSIRO Division of Plant Industry Tarnab, P.O. Box 446 Private Bag P.O. Peshawar 25000 Wembley, WA 6014 PAKISTAN AUSTRALIA E-mail: mohsin@psh.paknet.com.pk E-mail: s.asseng@ccmar.csiro.au Tel.: 92 91 2964058 Tel.: 61 8 93336615 Fax: 92 91 2964059 Fax: 61 8 93878991 TUN-9992 FRA-10168 Dr. Mohamed MECHERGUI Dr. Florent MARAUX Institut National Agronomique de Tunisie CIRAD 43, Avenue Charles Nicolle B.P. 5035 1082 Tunis 34032 Montpellier Cedex 1 TUNISIA FRANCE E-mail: mechergui.med@inat.agrinet.tn E-mail: maraux@cirad.fr Tel.: 216 1 892785 Tel.: 33 4 67615645 Fax: 216 1 799391 Fax: 33 4 67615642 SEN-10403 IND-10170 Dr. Modou SENE Dr. Robert MYERS Institut Senegalais de Recherches Agricoles International Crops Research Institute for the (ISRA) Semi-Arid Tropics (ICRISAT) Route des Hydrocarbures P.O. Box 776 Bel-Air, B.P. 3120 Bulawayo Dakar ZIMBABWE SENEGAL E-mail: R.Myers@cgiar.org E-mail: isracrak@refer.sn Tel.: 263 83 8311 Tel.: 221 9736050 Fax: 263 83 8253 or 8307 Fax: 221 9736052 SYR-10174 ZIM-10175 Dr. John RYAN Dr. Trust SITHOLE International Center for Agricultural Research Ministry of Lands and Agriculture in the Dry Areas (ICARDA) Department of Research and Specialist P.O Box 5466 Services Aleppo Soil Productivity Research Lab. SYRIA Private Bag 3757 E-mail: j.ryan@cgiar.org Marondera Tel.: 963 21 213433/77 or 225112/012 ZIMBABWE Fax: 963 21 213490/225105/219380 Tel.: 263 79 23621 Fax: 263 79 24279

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Annex 2

PROGRAMME

RCM on "Management of Nutrients and Water in Rainfed Arid and Semi arid Areas for Increasing Crop Production" (D1.20.06)

Tunis, Tunisia, 6 - 10 March 2000

Monday, 6 March

09:00 Official Opening

INAT or Ministry of Agriculture

Representative of FAO

09:30 Remarks by Scientific Secretary, Mr. P. Moutonnet

09:45 Remarks by local organiser, Prof. M. Mechergui

10:00 - 10:30 Coffee break

Session 1. Chairman: A. Bationo (IFDC/ICRISAT-Niger) 10:30 - 11:45 Mohamed Mechergui, Snane Mohamed Habib, Bouhajba Abdellaziz and Nada Mahjoub (Tunisia) Management of nutrients and water in rainfed arid and semi-arid areas for stabilising and increasing cereal and forage crop production in Tunisia 11:45 - 12:30 Isaya V. Sijali (Kenya) Optimisation of water and nutrient use in rainfed semi-arid Kenya through integrated soil, water and nutrient management practices 12:30 - 14:00 Lunch break

Session 2. Chairman: R.J.K. Myers (ICRISAT-Zimbabwe)

14:00 - 14:45 Issaka Mahaman (Niger)

Impact of organic and inorganic fertilisers on soil productivity of

Western Niger (Sahel area)

14:45 - 15:30 Andre Bationo (Niger)

(absent, paper presented by Issaka Mahaman)

Integrated plant nutrients management in the West African semi

arid tropics

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15:30 - 16:00 Coffee break

16:00 - 16:45 Trust Sithole (Zimbabwe)

Management of nutrients and water in rainfed arid and semi-arid

areas for sustainable crop production

16:45 - 17:30 Modou Sene (Senegal)

Improving and sustaining food crop production by reversing soil

nutrient depletion and water loss

Tuesday, 7 March

Session 3. Chairman: Fl. Maraux (CIRAD-France)

09:00 - 09:45 Khalil El Mejahed (Morocco)

Impact of green manure and fertiliser on soil quality and

profitability of wheat fallow system in semi-arid Morocco using

nuclear techniques

09:45 - 10:30 Daniel R. Prieto (Argentina)

Improving water and nutrients management in the rainfed

cropping system of Santiago del Estero, Argentina

10:30 - 11:00 Coffee break

Session 4. Chairman: J. Ryan (ICARDA-Syria)

11:00 - 11:45 Florent Maraux (France)

Water and nitrogen uptake (measuring and modelling) of rainfed

maize under conservation tillage in semi-arid Mexico

11:45 - 12:30 Deifallah M. Badarneh (Jordan)

Enhancement of nitrogen and water use efficiency by optimising

the combination of soil, crop and nitrogen management

12:30 - 14:00 Lunch break

Session 5. Chairman: S. Asseng (CSIRO-Australia)

14:00 - 14:45 John Ryan (Syria)

Nutrient and water dynamics in long-term rotation trials

14:45 - 15:30 M. Mohsin Iqbal (Pakistan)

Increasing crop production in rainfed areas by improved water

and nutrient management using nuclear techniques

15:30 - 16:00 Coffee break

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16:00 - 16:45 Venkata Ramana Maparla (India) Management of nutrients (N and P) and water in rainfed sorghum-castor based cropping system of semi-arid tropical Southern Telangana Zone 16:45 - 17:30 Manbir Singh Sachdev (India) The use of nuclear techniques to improve management practices and increase crop production in rainfed areas with limited water resources Wednesday, 8 March Field scientific tour near Tunis organised by Prof Mohamed Mechergui

Thursday, 9 March Session 6. Chairman: Ms. Lee Heng (IAEA)

09:00 - 09:45 Gui-Xin Cai (People's Republic of China)

Field study of water and nitrogen efficiencies under rainfed

wheat by the combined use of neutron moisture meter and "N

labelled fertiliser.

09:45 - 10:30 Robert J.K. Myers (Zimbabwe)

Strategies for improved soil, water and nutrient management in

dry savannah systems

10:30 - 11:00 Coffee break

11:00 - 11:45 Senthold Asseng (Australia)

Application of a crop model to examine the efficiency and

sustainability of farming in areas of large climate variability

11:45 - 12:30 Ms. Lee Heng (IAEA)

The use of plant growth simulation models for synthesising

scientific results obtained through CRP D 1.20.06

12:30 - 14:00 Lunch break

Session 7. Chairman: P. Moutonnet (IAEA)

14:00 - 17:00 Discussion on experimental plans, and the use of simulation

models.

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Friday, 10 March Session 8. Chairman: P. Moutonnet (IAEA)

09:00 - 10:30 Final discussion: upgrading of experimental guidelines and work

plans. Collection of progress reports and summaries.

10:30 - 11:00 Coffee break

11:00 - 12:00 Closing session.

12:00 - 14:00 Lunch break

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Annex 3

SUMMARIES OF PRESENTATIONS

ARG-9985: D. Prieto Improving water and nutrients management in the rainfed cropping system of Santiago del Estero, Argentina The period reported (October 98-February 2000) includes the complete 1998-1999 growing season (November-May) of the main crops (Cotton and Maize), the 99 winter season (only alfalfa in the field), and the still not finished second growing season (99/00) of the main crops. Materials and Methods: Split plot field trial was carried out at INTA-Santiago Experimental Station. The main plot consists of soil tillage (conventional vs. direct seeding). Subplots consist of fertiliser N treatments (0 vs. 50 N units/ha in cotton; 0 vs. 60 N units/ha in maize). Ultimately, the crop-pasture (alfalfa) rotation will be evaluated against traditional continuous crop (cotton and/or maize). Changes of soil moisture, estimation of crop water use, water extraction pattern were studied on cotton, maize and alfalfa plots weekly from neutron probe measurements (Troxler 3333). Crops growth and yield response were studied in the 1998-1999 field trial using the following growth indicators: Cotton: plant height, fruits mapping, boll weight, seed and fibre yield, % of fibre. Maize: plant height, number of cob/plant, number and weight of seed (all measurement were done at harvest time) Alfalfa, determinations include: number of plants (once a year), dry matter production per harvest, dry matter changes on the main part of the plant. In cotton plots of the 1999-2000 field trial plant height, number of nodes, fruits mapping and dry matter on the main part of plants, leaf water potential and stomata resistance were measured every 7 to 15 days. Urea was the source of N fertiliser. Urea 5%'SN enrichment was used on micro-plots (4mz in cotton, 2,8 in' in maize) to determine fertiliser use efficiency and N use by the crops. Deviation of the C isotopic ratio was also determined in order to investigate the differences in water use efficiency. Soil and climate information were collected in order to validate crop growth models. Precipitation in the 98-99 growing season (November- May) was 546 mm, that is 11 % greater than the historical values, the "winter" rainfall (May-October) was 113 mm ( 74 mm in October), while in the 99-00 season the amount of rainfall until February 21 st were 413 mm. Results: In the 1998 trial, differences on cotton yield between soil tillage and fertilization treatment were not statistically significant (a=5%). Interaction between soil tillagefertilization was also not found. Maize yield differences between soil tillage treatments and interaction soil tillage-fertilization treatments were also not significant. However fertilization (60uN) significantly affected yields. N plant analysis and use of 'SN show that in cotton: i) the amount of N in bolds were not different between fertiliser treatments, ii) 13 % of the recovery in the 50uN treatments came

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from the urea, iii) the % of fertiliser recovery on the bolds was 23,75%. In maize, i) N amount in grains was statistically different between 0 and 50uN treatments, ii) 9 % of the recovery came from the fertiliser in the 50uN treatments, iii) the fertiliser recovery in grains was 20 %. 8'3C results show no differences between soil management and fertilization treatment on both crops, cotton and maize except on maize grain. Growth of alfalfa during the dry season were better than expected, dry matter production were similar to the mean values of irrigated crops. However the crop suffered water stress at the end of the dry season and its productivity and number of plant/m2 decreased. The report also includes some preliminary results from the 99-00 growing season and proposes some change in the field trial to achieve the objectives.

AUL-10951: S. Asseng Application of a crop model to examine the efficiency and sustainability of farming in areas of large climate variability The simulation analysis with APSIM Nwheat has indicated that yield, water and nitrogen use efficiency of wheat crops in the Mediterranean climate of Western Australia vary markedly depending on soil water holding capacity, N management, rainfall amount, and in particular seasonal rainfall distribution. Thus, a simulation modelling approach, when combined with long-term climatic data and regional soil information is able to greatly extend the interpretation possible from limited experimental studies. The results have suggested that the greatest potential for increasing yield, WUE and NUE exists in the medium/high (400-500 mm annual rainfall) and medium rainfall (350-450 mm) regions on soils with high water holding capacity (110 mm PAW). The analysis also highlights the yield advantage on sandy soils (50 mm PAW) in low rainfall years and therefore mostly in the low rainfall region (<350 mm). On the clay soils in the low rainfall region early sowing and the presence of stored water in the profile both provide opportunities for increasing yields and should be taken in consideration when making N management decisions. The forecast of probabilities of wheat grain yields at the end of May is possible in Western Australia using the Southern Oscillation Index (SOI) in relation to simulated grain yields based on the SOI in May-April. The signal is strongest for positive (high yield potential) and negative SOI (low yield potential) in the low rainfall region and also varies with soil type due to soil water characteristics.

In a current simulation analysis, APSIM Nwheat has been used to support the breeding evaluating process of physiological characteristics in wheat aiming on increasing potential yield by quantifying yield advantages of new traits across seasons, locations and soil types.

To extend the modelling work to other crops and crop rotations a Post-Doctoral Fellow has been appointed working on canola and lupin modelling, a PhD student working on lucerne modelling and a visiting scientist working on extending the application of the wheat model, have joined the project. An additional scientist has been employed by CSIRO Plant Industry in Canberra working on wheat modelling in New South Wales and in close collaboration with us. A two week training workshop on using APSIM has been conducted over the last months with the new users.

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CPR-9986: G.-X. Cai Effect of nutrient and mulching management on the efficiency of nitrogen This report summarises the results obtained in the ls` year field experiment (Sept., 1998 - June 1999) in Changwu, China. It includes 2 sets of experiments, each one has 4 treatments with Latin Square design. Phosphate at a rate of 75 kg/ha of P205 was applied to all treatments. Fertilisers including N, P and organic fertiliser were applied as basal dressing. The 4 treatments were: CK (without N), N1 (100 kg/ha of N as urea), N10 (100 kg/ha of N as urea and 50 kg/ha of N as organic manure) and N2 (150 kg/ha of N as urea). 'SN study was carried out in 3 of the treatments: N1, N10 and N2, with 4 replicates. The other set experiment was set up for study of effect of mulching planting. Results showed that the efficiency of urea at a rate of 100 kg N/ha with and without organic manure was good. Wheat grain yield was 2.8 t/ha in treatment CK and it increased to 4.0 t/ha for N l and 4.3 t/ha for N 1 O. When application rate increased to 150 kg N/ha grain yield decreased to 3.7 t/ha, indicating that the application rate of 150 kg N /ha as urea was too high in the dry year. Mulching planting is very successful for maize in the region. However, wheat yield was not significantly increased by using mulching planting in comparison with traditional planting probably due to the lower plant density and lower efficiency of fertiliser use for the latter. Water use efficiency (WE) was 7.6 kg/ha/mm for CK and it increased to 9.7-11.7 kg/ha/mm for the treatments with application of N fertiliser. The highest WUE was shown in a treatment of mulching planting. Results of "N study showed that plant recovery and N remained in the 0-40 cm soil were in the range 36.6-38.4% and 29.2-33.6% of the applied N, respectively, in the 3 treatments of N 1, N 10, and N2. Thus the amount of applied N not recovered ranged between 29.5-34.2%. It was concluded that rational fertilization is an effective management practice to increase efficiency of water and nutrient utilization in rainfed wheat in Changwu region. Mulching planting did not show any effect on crop yield; this should be further studied.

FRA-10168: F. Maraux Water and nitrogen uptakes (measuring and modelling) of rainfed maize under conservation tillage in semi-arid Mexico

CIRAD has been working for many years, in partnership with INIFAP and CIMMYT, and with the scientific support of INRA, on the assessment of the effects of crop residues mulching on the transfer of water and nitrogen in fields cultivated with corn under conservation tillage practices in the State of Jalisco, Mexico. Part of these studies were done at the plot scale (A. Findeling), and others at the State scale (M. Arreola)

Direct effects of mulching were shown on runoff and soil evaporation, indirect effects on the plant architecture (rooting system and leaf area development). Both play an important role on the water consumption of the maize crop, and finally on the dry matter and grain yield. Effects were also observed on the soil structure, particularly for the soil surface.

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On plot scale these effects were studied, first with independent protocols, then simultaneously, and finally A. Findeling grouped them in a comprehensive model which describes the functioning of soil/crop system. In the course of his study, it appears that the major effect of mulching consists in the limitation of runoff, and that this effect, which starts even from low levels of mulching, is mainly due to the modification of the soil structure in the contact zone (on a few millimetres) between soil and crop residues during their biodegradation. The final model, under development, will try to take into account these effects, and to combine them with water and nitrogen transfer modules. M. Arreola has studied a simplified soil / water / corn model, taking into account effects of crop residues on water (runoff and soil evaporation components) which was spatialised using GIS and included soil, slope, and climatic data. The model was run pixel by pixel, and the outputs (yield, biomass, run-off, etc.) were spatialised and mapped. Conservation tillage potentialities depending on the geographical location were drawn for the whole State of Jalisco.

IND-10169: V.R. Maparla Management of nitrogen and evaluation of water use efficiency in traditional and improved cropping systems of Southern Telangana Region Southern Telangana region of Andhra Pradesh, India contains degraded red soils of poor fertility, and is home to resource-poor farmers. Production of sorghum-castor systems is limited by low and variable rainfall, and by nutrient deficiency, mainly nitrogen. With a view to improving the well-being of the farmers, there is a need to develop higher yielding, sustainable sorghum-castor based production systems. This research, which is collaborative between ANGRAU and ICRISAT has been established on research station and farmers'fields in the Mahaboobnagar district. The on-station work was conducted with 4 cropping systems (2 year rotation) viz. SorghumCastor; Castor-Sorghum; Sorghum/Pigeonpea-Castor and Castor- Sorghum/Pigeonpea in main plots and 4 nitrogen management options (control; farmyard manure (FYM) @ 1.5 t ha'; 60 kg N ha' as urea and FYM @ 1.5 kg t ha' + 45 kg N ha' as urea) in subplots laid out in split plot design with 3 replications. The crops were sown in July 1949. Microplots containing "N-labelled urea and FYM were established and neutron access tubes for monitoring soil water were installed. Sorghum was harvested in November; castor and pigeonpea were finally harvested in December. Higher stalk yield, grain yield and total dry matter were produced with sole sorghum compared to intercropped sorghum. Among the different N management options studied, application of urea resulted in higher grain yield (2090 kg ha') compared to that of FYM application (880 kg ha'), and control (469 kg ha'). However, this was at par with that of combined FYM urea (2000 kg ha'). Similarly higher total dry matter of sorghum was realised both with urea and with that of combined FYM urea compared to FYM alone and control plots. With FYM and also with control plot, sole sorghum and intercropped sorghum did not differ much in terms of grain yield. However, with urea or combined FYM + urea, sole sorghum gave more grain yield than intercropped sorghum. The grain yield of pigeonpea did not vary significantly due to various N management options imposed to sorghum crop in sorghum/pigeonpea intercropping systems. Among different N management options tested, application of urea gave higher seed yield (1620 kg ha'), stalk yield (2040 kg ha') and total

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dry matter (3660 kg ha') of castor compared to other N options. However, it was at par with that of combined FYM + urea (1500, 1910 and 3450 kg ha', respectively). The plant and soil samples from microplots were sent to International Atomic Energy Agency for "N analysis. The results of on-farm research indicated that higher yield levels were observed with improved cropping system compared to that of farmers practice. The grain yield of sorghum in farmers practice varied from 540-1010 kg ha', while in improved practice, it varied from 1440 to 1729 kg ha'. Similarly, yield levels of castor ranged from 400-800 kg ha' with farmers practice, while it was 800 to 1380 kg ha' in improved practice. The results from 1999 were very good considering that it was regarded as drought year. The yields greatly exceeded average yields obtained by farmers in the region. The on-farm results, obtained by farmers testing improved practices, also greatly exceeded yields obtained by other farmers in the region. This research will continue in the 2000 growing season as per the planned rotation cycle.

IND-10170: R.J.K. Myers The potential contribution of isotope-aided experimentation to participatory action research and modeling to help smallholder farmers in the semi-arid tropics Farming in the semi-arid tropics (SAT) is risky, due to primarily water and nutrient constraints. Isotope-aided methods have potential to answer questions related to resource constraints experienced by farmers. This paper asks whether isotope-aided methods are fulfilling this objective, and suggests ways in which we could improve our effectiveness. I will use as an example the current ICRISAT-ANGRAU experimentation in India, but also refer to the approach being used in ICRISAT research in Zimbabwe. I shall stress the need to use modern tools, and to involve researchers, farmers, advisers, and grain traders in implementing participatory action research linked to systems simulation to reduce the time taken in research and development. The current research in India links on-station research using "N methods with four cropping systems to on-farm research that contrasts selected rotations with farmers' practice. In Zimbabwe, in areas with similarities to the Indian site, we seek to find ways to help farmers overcome constraints to adoption of water and nutrient management technologies. In both the Indian and Zimbabwean regions being studied, past attempts to promote adoption of water and nutrient technologies have been unsuccessful.

In Zimbabwe, researchers and extension specialists are using scenario analysis with the APSIM simulator as a precursor to on-farm participatory action research to assist farmers in maize, sorghum and millet areas of Zimbabwe and Malawi. We are addressing questions that are important to our farmer clients, particularly questions related to fertiliser and manure use. In future, we plan to extend this activity to involve farmers directly in the process.

Is there a role for experimentation that includes isotope-aided methods? Usually experimentation has remained a considerable distance from implementation at the farm level. With the need for research to have more impact, value-adding must be carried out, assisted by the use of modern tools such as simulation, GIS, etc. In order to invest more in value-adding, there will be less to invest on experimentation. Experimentation will therefore need to be

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`smarter' and more targeted, using tools such as isotope-aided methods. In ICRISAT, we anticipate the need for technology improvement in relation to water - increased water use efficiency would make major impacts on dryland agriculture, and nitrogen, where increased water use efficiency would also have major impact. Isotope-aided methods have a role to play here. There are many questions to be answered - Are new legumes efficient nitrogen fixers? Is farmyard manure (an under-utilised resource in Zimbabwe) a useful supplier of nitrogen and phosphorus? Is poor utilization of fertiliser N a deterrent to farmer adoption? How much `drought-proofing' can be obtained through better on-farm water management?

IND-9987: M.S. Sachdev Use of nuclear techniques to increase fertiliser nitrogen and phosphorus use efficiency in mustard and wheat in rainfed conditions

A field experiment was conducted in the Todapur Block of the Indian Agricultural Research Institute farm with Mustard (Brassica juncea) and Wheat (Triticum aestivum). The soil of the experimental site is alluvial loam belonging to Mehrauli series and has been classified as coarse loamy non-acid hypothermic typic Ustochrept. The experiment was laid-out in a randomised block design with four replications with three levels of N and P ( Mustard : 0, 30 and 60 kg N ha' and 0, 15 and 30 kg P205 ha' ; Wheat: 0, 40 and 80 kg N ha-' , 0, 20 and 40 kg P205 ha' ). The main plot size for mustard crop was 6.0 m x 3.0 m (18 m2) and for wheat crop 5.0 m x 3.0 m (15 mz). In treatments N, and NZ in each main plot a microplot of size 1.0 m x 1.0 m (1.0 in') was made for 'SN-urea (labeled with 5.007% atom excess 15 N) application. Also in treatments where P, and P2 levels of phosphorus were applied a separate microplot of 1.0 m x 1.0 m (1 m2) in each main plot was made for application of 32P labeled single superphosphate (specific activity 0.5 mCi 32P / g P205 ). N was applied through urea and P through single superphosphate (16 % P205) in main plots. To both mustard and wheat crops nitrogen was given in two splits and P and K were applied in single application as basal broadcast and incorporated. To mustard crop half the N was applied at sowing as broadcast and incorporated in soil and the remaining half was top-dressed at pre-flowering stage. To wheat crop one-third N was applied at sowing as broadcast and incorporated in soil and the remaining two-third at ZADOC-30 stage as top-dressed. Mustard crop (cv T-59) was sown on October 13, 1998 and wheat (var. WH-147) on October 16, 1998. The results on seed / grain, stover / straw yield, nitrogen and phosphorus contents, total and fertiliser N and P uptake and fertiliser use are reported. There was wide variation in the dry matter yield recorded at Z-30 sampling in wheat amongst replications and N and P contents were more in N or P fertilised plots compared to check plots. At pre-flowering stage in mustard the total N uptake was nearly 70% and total P uptake was about 85% of the total uptake of these nutrients at harvest. At harvest mean seed yield of mustard was 0.44 Mg ha' in N°, 1.10 Mg ha' in N3° and 1.30 Mg ha' in N6° plots. The highest mustard seed yield of 1.4 Mg ha' was obtained with highest application of N and P. In wheat crop the highest grain yield of 1.78 Mg ha' was obtained with 80 kg N ha' and 40 kgP205ha-' fertiliser application. Both in mustard and wheat the increase in mean yield was more pronounced with N application than P fertilization.

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The fertiliser N use efficiency in mustard ranged from 34.19 to 64.25 % and in wheat from 24.22 to 43.75 %, respectively. The fertiliser P recovery in mustard was from5.26 to 30.05 and in wheat, 4.16 to 15.34 %. The mustard crop extracted more water from soil compared to wheat crop under rainfed conditions. In both mustard and wheat nearly 95 % of the applied fertiliser N could be recovered in either crop or soil.

JOR-9988: M. Mohamad Rusan Enhancement of nitrogen and water-use efficiency by optimizing soil, crop and nitrogen management A field experiment was carried out at Maru Agricultural Research Station 100 km north Amman, Jordan. The experiment, a split-split plot design within four replications investigated wheat crop residues and nitrogen fertiliser levels on the subsequent wheat crop in three crop rotations. Crop rotation was the main plot, wheat residues the sub-plot, while N level was the sub-sub plot. The rate of N was 40 and 80 kg/ha as urea, enriched with 5.717% "N a.e. and added to 2m' micro-plot. Lentil was treated with 20 kg N/ha. The total annual rainfall was 184 mm during the whole season and was poorly distributed. One-half of the lentil plots did not germinate, while the growth of wheat was poor. The results were calculated on 1 m row in the micro plot treated with "N. Both the biological and the grain yields, in addition the harvesting and N indices and the amount of Ndff, were very low. Based on the procedure of sampling, N recovery was less than 2.5%. Most of the N in the biological and grain yields was derived from soil. The amount of N fertiliser left in the soils was not detectable. The wheat residues at high N level decreased the amount of N yield. Because of the low yields caused by drought, valid or meaningful data were not in evidence.

KEN-10330: LV. Sijali Optimization of water and nutrient use in rainfed semi-arid Kenya through integrated soil, water and nutrient management practices

A report is presented on the research conducted from 1998 to 1999, in the fields of soil and water management under arid and semi-arid conditions. One on-station site was selected in the Semi arid Machakos district. Soil samples were collected for both chemical and physical characterization of the site. Two cropping seasons field experiments, March - June, 1999 (long rains) and October, 1998January, 1999 (short rains), were conducted with pure maize stand. A split-plot randomised factorial design was used with the treatments, as soil and water management; flat cultivation (SWM,); ridging (SWMz). Nutrient management with respect to nitrogen only, consisted of wholesome application at emergence (time 1); wholesome application when the crop is at knee height (time 2); and equal splits application at times 1 and 2.

Soil chemical characterization indicated that major nutrients were in adequate supply except for carbon (organic matter) and hence Nitrogen that was low. Most farmers in the area do not apply farm yard manure even though the soils have low organic matter content.

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The short rainy season crop was influenced by drought "lanina phenomenon" that made it impossible to apply the second split of N application at knee high stage. Furthermore, the crops dried quickly with loss of dry matter due to blowing away of above ground plant parts because of strong winds. The long rainy season crop developed up to maturity and was harvested for all component analyses. Results on grain yield indicated differences(P = 0.091) between the water management treatments but having very little effect of N treatment (P = 0.432) and S WM-N interaction effects( P = 0.333). Strong N treatment effects were found on total N uptake and fertiliser use efficiency (FUE). Higher FUE (29.2%) was found with wholesome application of N at plant emergence. Split application was also superior in FUE(27%) compared to the recommended practice, which gave FUE less than 4%. Increased yields of maize grain did not however accompany the improved N use efficiency. Treatment effects on carbon isotope discrimination (8'3C)of whole plants were not so pronounced (P>0.23).

MOR-9989: K. El Mejahed Green manure and N fertiliser in soil quality and profitability of wheat-based systems in semi-arid Morocco using nuclear techniques The objective of this study was to assess substitution of fallow with green manure and its impact on wheat yield, N-fertiliser input, the profitability of the wheat fallow-based system, soil properties and water and N-use efficiencies using nuclear techniques, in order to sustain soil productivity and ensure environment protection. Field experiments were conducted at two experiment stations with different mean annual rainfall. Measurements were taken at planting and harvest on soil N, C, OM, nitrate, Stability Index and water. Measurements for wheat consisted of grain and straw yield, N uptake, %Ndff, NUE, WUE and analysis of "N and 8'3C. The 1998-99 year was dry, with a rainfall of 177 at J. Shaim and 194 mm at J. Riah. Wheat grain and straw, N uptake, NUE and WUE were significantly higher only at J. Riah for the wheat/fallow (W/F) when compared to either wheat/vetch mowed or incorporated. Grain yield in W/F was twice that of the other rotations. Based on 8'3C, W/F was more efficient in both locations. %Ndff for both grain and straw was higher in W/F. Incorporated vetch increased OM in both locations but the increase was significant only at J. Shaun, with no effect on the Stability Index. The effect of applied N on wheat in different rotations differed with locations and rotations. In general, wheat yield was highest without N application and lowest with N application at sowing and tillering or both. Soil water at different depth and periods differed from one rotation to another only at J. Riah, since the rainfall received at J. Shaun was too small. N treatments did not have an effect on soil water.

NER-10402: Issaka Mahaman Impact of organic and inorganic fertiliser on soil productivity in Niger

Soil fertility has been identified as the main constraint to crop production in Niger. In order to overcome this constraint the use of fertiliser is recommended. However, it is recognised that mineral fertiliser alone is not sufficient to increase crop production. Therefore, a combination of different technologies is required to restore soil fertility. A three year study was undertaken on a sandy soil at Tama research station to determine the combining effect of

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mineral and organic fertiliser on crop production. The use of "N was considered to determine N fixation by a cowpea crop in a rotation system. The cropping systems consisted of continuous millet, a rotation of millet-cowpea and millet-cowpea intercrop. Three levels of P (0, 20 and 40 kg P205/ha) and 3 levels of N (0, 30 and 60 kg N/ha) combined to 3 levels of organic fertiliser (0, 0.9 and 2.7 t/ha) were used in a split plot design. The combined effect of mineral and organic matter with 40 kg P205/ha, 60 kg N/ha and 2.7 t/ha of organic matter increased millet grain yield by 87% and cowpea grain yield by 200% in a continuous cropping system. The same increase in yield has been observed with the milletcowpea intercrop. The cowpea grain yield increased by 100 to 230% due to combined fertiliser application. The nitrogen N fixation by cowpea was found to be not affected significantly by the treatments, however, the highest value of %Ndfa was obtained with the lowest level of mineral fertiliser and no organic fertiliser. No significant difference has been found between the value of d '3C of the different treatments, however, values for millet crop are higher than those of cowpea.

PAK-9990: M.M.Iqbal Tillage and nutrient management for yield and fertiliser utilization by rainfed wheat and lentil The major constraint in dryland agriculture is inefficient nutrient and water use. Field experiments were conducted during 1998-99 at the Nuclear Institute for Food and Agriculture (NIFA), Peshawar, Pakistan Research Station and two farmers' fields to test the response of cropping sequences (cereal-cereal, legume-cereal and legume/cereal intercropping) to tillage systems (conventional tillage, no tillage) and nutrient levels (Nbo+P3o and Nbo + Pbo) on yield, fertiliser utilization, and C isotopic discrimination ratios. "N-labelled urea was used to study nitrogen-use efficiency by wheat at NIFA and to assess biological N fixation by lentil under farmers' field conditions. Tillage treatment improved the grain, straw and root yields of wheat at NIFA and at one farmers field (at Urmar). The N yield and fertiliser-N uptake were also increased under tillage at these sites, but P levels exerted no effect. At the other farmer's field (Jalozai), grain and straw yields were increased under no-tillage, and N yield and fertiliser-N yield were favourably influenced by the higher P level rather than by tillage treatment. These differences in farmers' field might be due to differences in soil types and the previous cropping history. Fertiliser utilization was generally higher at farmer's field (up to 42% at Urmar and 40% at Jalozai) than at NIFA Research Station (up to 33%). This could be due to nutrient hunger of farmers' soils.

In case of lentil, tillage and nutrient treatments did not significantly influence grain and straw yields, but N yield and fertiliser-N yields were increased at higher P level and generally under tillage. Nitrogen fixation by lentil was also stimulated by the higher P level. Total plant-N in lentil was up to 6% from applied fertiliser, 82 - 96% from atmospheric fixation, and up to 12% from soil. The amounts fixed varied from 42 to 91 kg/ha in different treatments.

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The data on C discrimination at farmers' field revealed that delta values in wheat straw were significantly higher under tillage and slightly higher under the higher P level. The differences in tillage treatments at farmers' fields were more pronounced at early crop growth stages, but the differences narrowed as growth progressed. The results so far obtained demonstrate that with proper management, efficiencies of water and nutrient use could be increased at farmers' fields.

SEN-10403: M. Sene Improving and sustaining food crop production by reversing soil nutrient depletion and water loss I. Phosphogypsum efficiency to correct soil P deficiency and/or soil acidity. To boost the agricultural production, the nation wide four-year programme started in 1997 uses phosphogypsun (PG) and Taiba phosphate rock (PR) mix as soil P amendment source to correct soil P deficiency and/or acidity. However, there is no previous study proving the efficiency of PG correct these soil deficiencies. A long term experiment has been set up in 1997 at Nioro agricultural research station to study the efficiency of PG and PR/lime to increase crop yields for a corn/peanut rotation and to improve soil P and pH status. A randomised complete bloc design composed of 8 treatments and 4 replications was used. The amendments applied once every 4 years were based on a recommended rate for PR (400 kg/ha). For the PG amendment, the application rate was derived from the P content obtained after chemical analysis of the fertiliser material (1000 kg/ha). The treatments were: control with no P or Ca added (TO), P added as Triple Super Phosphate at the rate of 30 kg/ha P205 (T1), 0% PR + 100 % PG (T2), 25% PR + 75% PG (T3), 50% PR + 50% PG (T4), 75% PR + 25% PG (TS), 100% PR + 0%PG (T6) and 400 kg/ha lime or 100% lime (T7) Soil samples were collected on each plot after each corn harvest in 1997 and 1999. The analyses performed on those samples included pH, total carbon, total nitrogen, base elements, CEC and aluminium. In 1997, no significant direct effect was observed on corn yield components. Corn grain yields were low and ranged from 750 to 1100 kg/ha. The low yield was mainly due to below average rainfall in 1997. Nevertheless, the analysis of soil samples taken after harvest showed a low soil fertility status, especially a low pH, but also a significant Ca movement within the soil profile. In 1998, residual effects of treatments was significant only on pod yield of peanut. As compared to the control, all the treatments (except TS) improve significantly the peanut pod yield. This confirmed the positive effect of Ca application on pod filling. The leaf analysis has not shown any significant treatment effect, despite some plant chlorosis that was observed. In 1999, with above average rainfall, also low corn yields were obtained. No significant treatment effect was obtained on corn yields. The analyses of soil samples have shown evidence of poor soil fertility conditions for most treatments, especially the soil pH which remained low (pH<5.5). Regardless of the treatment, the corn N use efficiency was low.

II. Effect of manure and P-source fertiliser on the optimisation of soil water and nutrient use for the main cropping system in Senegal peanut basin. A four-year nation wide programme currently being conducted in Senegal aims to improve food and cash crop production. P and Ca soil amendment using natural resources based fertilisers is one of the strategies considered. A network of long term randomised complete bloc design experiments was set up in 1997

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within each of the three main cropping system in the Senegal Peanut Basin. While both onstation and on-farm trials are installed in the corn/peanut cropping system, only one on-farm experiment was conducted in a continuous rice cropping system. The five treatments under comparison were: control with no P or Ca added (TO), P added as TSP at the rate of 13 kg/ha (T1), phosphogypsum and phosphate rock (PG + PR) mix at the rate of 700 kg/ha (T3), manure at the rate of 3000 kg/ha for the continuous rice cropping system and 5000 t/ha in the corn/peanut cropping system (T4), and (PG + PR mix combined with manure (TS). Soil fertility changes have been measured from soil samples collected on each plot from the onstation trial in 1997 and in 1999 after corn harvest. Crop water balance has been determined using neutron probe and tensiometers while 15-N labelled fertiliser has been used in 1999 to determine the corn N efficiency use. For the experiment at Nioro Research Station in 1997 significant Ca movement was observed within the profile. Regardless the treatment, deep water percolation was observed both in 1997 and 1998, below average rainfall in these years. Corn and peanut yields were low. Soil pH remained very low (pH < 5.5), with the manure application alone or in combination with PG and PR mix tend to increase the soil pH value. Corn yields (grain and stalk) remained low for the second time (less than 2000 kg/ha, i.e., 50% of the corn variety potential yield value). Compared with the control treatment, the PG and PR mix had no significant effect on corn grain or stalk yield. However, the manure alone or combined with the PG and PR mix had a significant effect on yield. Despite the large amount of rainfall recorded in 1999, the crop water balance indicated a low water use efficiency. The drainage water accounted for at least 40% of the rainfall. After 4 years of experimentation, the results obtained indicated the PG and PR mix as applied does not show high efficiency in correcting P and Ca deficiencies.

SYR-10174: J. Ryan Long-term cereal-based rotation trials in ICARDA: Crop yields, water relations, nutrients and soil quality Despite the food surpluses and self-sufficiency that characterise the developed world, many countries, especially in the low-rainfall drought-prone regions, face seemingly insurmountable challenges in meeting their food needs. The lands bordering the Mediterranean in West Asia - North Africa (WANA) are typical of such regions. There farming systems involve rotations of cereals with fallow or food/forage legume crops, depending on location and rainfall, which is low (200-600 mm yi') with large annual and within-season variation. The cropping season coincides with the cool rainy period (November - May) when evaporation rates are low; this is followed by a dry hot summer. Drought invariably limits crop yields. Barley (Hordeum sativum L.) tends to dominate in the drier zones and bread wheat (Triticum sativum L.) and durum wheat (T. turgidum L. var. durum) in the more favorable areas. Sheep and goats are an integral part of the systems, particularly those dominated by barley. The International Center for Agricultural Research in the Dry Areas (ICARDA) is developing improved cultivars and management practices, and needs to critically examine cropping options and management in terms of efficiency, costs, and "sustainability". Only through multi-year or long-term rotation trials can such a perspective be developed. In a radical departure from one-year on-station or on-farm trials, ICARDA initiated several long-term trials in the mid 1980s. A range of issues were addressed in different locations,

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from drier (<300 mm) to more favorable (300-500 mm) environments. These included rotation trials that focused on tillage systems, stubble management, forage, barely, grazing, cereal/shrubs, and both two - and three - course rotations with wheat or barley. Two major trials were the "Barley/Legume Grazing" trial and the wheat-based "Cropping Systems Productivity" trial. This later trial was initially the prime focus of our concern in this project (CRP-7). This long-term trial was established in 1983/84 at ICARDA's main research station at Tel Hadya, near Aleppo in northern Syria, to evaluate the productivity of systems in which durum wheat was rotated with vetch (Vicia saliva L.), lentil (lens culinaris Medik), chickpea (Cicer arietinum L.) medic pasture (Medicago spp), watermelon (Citrullus vulgaris L. ), wheat, and fallow. Varying nitrogen (N) levels (0, 30, 60, 90 kg/ha) and intensities of grazing stubble (heavy, moderate, no grazing) were imposed on the wheat phase. Both the wheat and the alternative phase were included each year. Water measurements for selected rotations were taken with a neutron probe. Routine sampling was done in the fall each year for chemical analyses. In some rotations, microplots using "N facilitated the study of N dynamics. The effect of rotation and N were readily apparent, while the effect of grazing stubble was slower to manifest itself and had minimal effects. While seasonal rainfall, which ranged from 210 to 486 mm, and residual soil moisture after the alternate phase, dictated the magnitude of N response in the wheat-fallow rotation, N increased water-use efficiency. Relative wheat grain yields as a ratio to wheat-fallow rotation were about 95, 85, 85, 70, 70, and 45% following watermelon, vetch, lentil, medic, chickpea, and wheat, respectively. The concentration of N in grain and straw as well as total N uptake varied with the rotation and crop yield. Water-use efficiency followed the same trend as yields, with fallow being least efficient, while N increased total water use by wheat. Chickpea and medic tended to dry out the profile like wheat, but fallow, watermelon, lentil and vetch left some stored water for the following year's crop. As the trial progressed, attention was focused on soil indicators of sustainability. With time, there was a buildup of organic matter and total N, with values showing the same general, but unrelated, variation as yield parameters. Similarly, measurements of aggregate stability (wetsieved) were higher for the medic plots and least for continuous wheat. Values also increased with N fertiliser level. This index was reflected in infiltration and permeability measurements. Sharp differences occurred in labile and biomass forms of C and N; again, values were highest with legumes (medic, vetch) and least with continuous wheat. Bacterial biomass N and C were more sensitive to environment change. Measurements of Nmineralization using "N and inorganic N, both in laboratory and in the field, followed the same trend as organic C and total N. Net mineral N showed a strong seasonal effect. As the trial was terminated in 1988, based on a management decision to rationalise resources, an overview of the data sets from the entire 14 year period will be given. A similar type of trial, "Barley/Legume Grazing", with barley rather than wheat and a focus on vetch management systems (hay, grazing) as well as continuous barley and fallow was continued. This trial was of the same age and on a similar soil type in an adjacent field. Similar measurements were taken, except that 'SN was not used. Again, vetch - a more viable option for animal feed than medic - showed improved soil N and OM levels. Observations to date are presented. This trial is expected to continue for at least 5 years pending critical

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analysis of the findings and emerging trends. Such trials can provide valuable information of relevance to cropping systems throughout a large area of the WANA region.

TUN-9992: M. Mechergui Management of nutrients and water in rainfed arid and semi-arid areas for increasing crop production The 13C isotope discrimination, the "N and the water use efficiency (WUE) methods, together with the introduction of improved management and current farmer technologies with respect to fertiliser application, use of pesticides and herbicides, selection of cultivars and sowing density, were used in two fields (Borj El Amri and Zaghouan), at the farm level, to study differences between cropping sequences in minimum and conventional tillage. There was no consistency in the water status between treatments in Zaghouan and Borj El Amri stations. The average runoff losses, average ETR losses at different times during the growing season of wheat, were less for the minimum than the conventional tillage in both stations. Average total water losses from the top 30 cm soil profile and average water availability in the root zone were the same for all crops for the minimum and the conventional at both stations. Minimum tillage gave the highest water-use efficiency in Zaghouan for soft wheat, but was highest for wheat germ in the conventional treatment at Borj El Amri. At the station of Borj El Amri two opposite results were observed when comparing minimum and conventional tillage with respect to Nitrogen fixation, nitrogen derived from fertiliser and the soil. The total nitrogen absorbed was higher in minimum compared to conventional tillage, however nitrogen derived from fixation was less. The residual nitrogen in the straw and weeds was greater in the minimum than in the conventional treatment. The highest yields were achieved for vetch with minimum tillage, while the lightest yields for oats were achieved with conventional tillage. Highest yields and NUE were achieved with conventional tillage. A correlation between yield of total N kg/ha, total yield in wheat and 8'3C was found at Zaghouan. The best cost-benefit was obtained with three years rotation at Borj El Amri, and two years rotation (soft wheat/vetch-oats) at Zaghouan.

ZIM-10175: T. Sithole Management of nutrients and water in rainfed arid and semi-arid areas for sustainable crop production in Zimbabwe

Poor soil fertility and lack of rains during critical stages of plant growth has frequently resulted in reduced crop yields in semi-arid areas of Zimbabwe. Soils in communal areas of these semi-arid areas are generally of poor fertility due to a long history of nutrient mining without significant nutrient addition in the form of fertilisers and/or organic manure. The effect of the frequent droughts could be reduced through more efficient use of water and nutrients. Field experiments were established in 1998 at Makaholi and Buhera to study the effect of water conservation and nutrient inputs on maize yields. Tied ridging and open furrows between planting rows were tested as methods to improve water retention and

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utilization. Three fertility inputs were also evaluated - one fertiliser level, one treatment that combined fertiliser and goat manure (and one goat manure level). In the 1998-1999 season, water management did not affect either maize grain or stover yield, probably because the 1998-1999 season was exceptionally wet. Fertiliser inputs increased grain yield at Makaholi and stover yields at both sites. This study is continuing during the 1999-2000 season.

L.K.Heng The use of plant growth simulation models for synthesising scientific results obtained through CRP D1.20.06 The collection of experimental data from various countries of this CRP for building of a minimum dataset was set out at the beginning of the project in 1998. The data requested consists of information on the site (slope and aspect, characteristics that impact the amount of radiation received by crop; runoff from rainfall); daily weather during the growing cycle; characteristics of the soil at start of the growing cycle and management of the crop (seeding rate, fertiliser application, irrigations). It is hoped that data collected can be used in the running of DSSAT model (Decision Support System for Agrotechnology Transfer), to analyse the impact of management decisions (e.g. sowing dates, fertiliser rates, residue management, rotation selection), with the ultimate aims of improving yields and reducing the variability in food supply in this region, at the same time ensuring it to be environmentally sustainable. The compilation of data has been slow in going, probably because most of the experiments have just finished their first growing season. Of those who sent, it can be seen that a wide range of soil type exists within these countries, from very sandy soil in Zimbabwe to rather clayey soil in Morocco. Wide range of rainfall pattern is also observed. Simulation of DSSAT was carried out for a few countries. Experimental and simulated data from Irrigated Wheat CRP are presented for comparison.

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Annex 4 Models and Minimum Data Sets DSSAT: Decision Support System for Aerotechnology Transfer DSSAT is a computer software which allows access to: i) crop models, ii) databases (crop, soil, and weather), iii) strategy analyses (seasonal and sequence) to simulate mufti-year outcomes of crop management strategies. It is capable of simulating potential production, genetic coefficients for growth and development, water-limited and water and N-limited conditions. It can also evaluate risk and sustainability, handles spatial variability and GIS etc. DSSAT v3.5 can now simulate: - cereals (CERES) - Barley, Maize, Millet, Rice, Sorghum and Wheat - legumes (CROPGRO) - Dry Bean, Soybean, Peanut and Chickpea - root crops (CROPSIM) - Cassava and Potato - various - Sugarcane, Tomato, Sunflower and Pasture - User-defined crop Input data needed: A) Soil information 1. Soil Description (general profile description):

- Soil horizon (thickness, horizon description) - Soil classification (including texture code) - Soil color, slope - Permeability code (very slow, slow, moderately slow, mod, mod-rapid, rapid, v. rapid) - Drainage code (very poorly, poorly, somewhat poorly, mod well, well, somewhat excessively, excessively)

2. Soil Description by layer:

- Particle size distribution (sand, silt, clay %), % coarse fraction >2mm - Bulk density (g/cm'), permanent wilting point (cm3/cm3)#, field capacity (cm3/cm3)#, saturated hydraulic conductivity (cm/h)# - pH (water), pH (buffer) - Root quantity (very few, very few to few, few, few to common, common, common to many, many, matted, no roots) - Organic Carbon (%), total Nitrogen (%), AI saturation (cm3/cm3), CEC (cmol/kg)

3. Initial conditions:

- Water table depth (cm)# - Crop residue (kg/ha) and its N and P content (%) - Residual N & P (%) - Residual incorporation (%), residual incorporation depth (cm) - Previous crop name, previous crop root weight, previous crop nodule weight (kg/ha) - N03-N, NH4-N (mg/kg soil), soil water content (cm3/cm3), dates of measurement

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4. Planting: - Cultivar names - Planting & emergence dates, planting method, depth (cm) - Population at seeding, population at emergence, row spacing (cm)

5 . Irrigation - Effectiveness (%), application method, amount/irrigation (mm)

6. Fertilization

- Dates, amount, types, method of application 7. Chemical application

- Dates, material, amount, method, depth and target 8. Tillage

- Depth, date, method B) Other data to record

1. Daily Tmax, Train, solar radiation (or sunshine hours) and rainfall (mm), plus any long term weather records if available. 2. N03-N in rainfall (if important) 3. Dates of successive growth stages from planting to harvest 4. Harvest:

- yield and yield components - micro-plots harvesting (seeds and straw separately) for N%, 15N % atom excess and 813C

- soil sampling on micro-plots for N% and 15N % atom excess measurement

# only if available

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