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Nutrient Content ofPoultry Manures and theOptimum Rate for EggplantFruit Yield in a WeatheredTropical UltisolCarol N. Opara a & J. E. Asiegbu aa Department of Crop Science , University ofNigeria , Nsukka , Enugu State , NigeriaPublished online: 24 Apr 2012.

To cite this article: Carol N. Opara & J. E. Asiegbu (1996) Nutrient Contentof Poultry Manures and the Optimum Rate for Eggplant Fruit Yield in aWeathered Tropical Ultisol, Biological Agriculture & Horticulture: AnInternational Journal for Sustainable Production Systems, 13:4, 341-350, DOI:10.1080/01448765.1996.9754792

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Biological Agriculture and Horticulture, 1996, Vol. 13, pp. 341-350 0144-8765/96 $10 © 1996 A B Academic Publishers Printed in Great Britain

Nutrient Content of Poultry Manures and the Optimum Rate for Eggplant Fruit Yield in a Weathered Tropical Ultisol

Carol N. Opara and J.E. Asiegbu

Department of Crop Science, University of Nigeria, Nsukka, Enugu State, Nigeria

ABSTRACT

Three field experiments on West African eggplant (Solanum spp.) responses to rates of poultry manure conducted in a weathered tropical Ultisol between 1990 and 1991 are reported. The poultry manures collected from different locations differed markedly especially in their contents of the major fertilizer elements ofN (16--36%), P (17-43%), K (6--56%) and Mg (13-51%). A manure rate of 15 t ha-1 appeared satisfactory for eggplant production, although no quadratic response on eggplant fruit yield was observed at the highest rate of 20 t ha-1. Yield responses to manure application were best predicted by a linear function within the range of 0 to 20 t ha-1 manure. Fruit yield increases with increased manure application came essentially from more fruits harvested per plant and from higher average fruit weights. The leaf and fruit elemental concentrations were not increased in relation to increasing quantities of the elements supplied with increasing manure rates, in part due to possible dilution effects.

INTRODUCTION

Solanum melongena (aubergine) is the eggplant commonly grown in Europe and America. In West Africa however, other species like S. macrocarpon, S. incanum, S. aethipicum, S. gila and S. nigrum, are more popularly grown for the fruit and, in some cases also, the leaves and tender shoots. Production in Nigeria had mostly been by subsistence farmers under rainfed low input practices, and in mixtures with other staples. Such practices led to low yields. Large scale commercial producers now exist and desire information on input and practices to maximize yields. There is a gap in published information in respect of manuring of the West African eggplant. The present practice of extrapolating information on manuring practices from work on tomatoes is unsatisfactory. The Ultisols which constitute the main agricultural lands of

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342 CAROL N. OPARA AND J.E. ASIEGBU

southern Nigeria cover more than 70% of the total land area (Mbagwu, 1992), but they suffer the constraint of low reserves of essential plant nutrients and high soil acidity (Unamba-Oparah, 1985; Mbagwu, 1989). Use of organic manure is recommended for managing such soils to improve the nutrient content and other soil physical characteristics (Mbagwu & Ekwealor, 1990), and to sustain yields, especially with the current high costs of inorganic fertilizers. Poultry manure is a commonly available organic material source that can be profitably used. The optimum rate for use needs to be known for efficient utilization of resources.

The West African eggplants commonly cultivated fall into the categories of large-, medium- and small-fruited types. One cultivar from each of the three fruit size groups was chosen for the present investigation. The objectives were to assess the nutrient content in poultry manures from different locations and to evaluate the optimum manure requirements for the three West African eggplant types under field conditions.

MATERIALS AND METHODS

Location and land preparation

Three field experiments were conducted between 1990 and 1991 in the University of Nigeria, Nsukka, Nigeria Teaching and Research Farm situated at 06° 52' N 07° 24' W, 447 m altitude. The soil is a sandy loam Ultisol (Oxic Paleeustult) of the Nkpologwu series. At the start of each experiment the land which was previously under fallow was disk-ploughed and eventually disk­harrowed to a fine tilth before the plots were marked out. A composite soil sample from representative field locations was obtained in each experiment with a soil auger to a depth of 18 em for physical and chemical analyses.

Experimental layout

Experiment 1 was on the response of Solanum incanum cv. Marvelum to rates of poultry manure. Treatments comprised five poultry manure rates; 0, 5, 10, 15 and 20 t ha-1, arranged in a randomized complete block design with eight replications. Each plot measured 3.6 m x 12.0 m. The seed was sown in nursery boxes on 7th June and transplanted into the field plots on 1st August, 1990.

Experiment 2 studied the response of three eggplant varieties to the five poultry manure rates. The eggplant were Solanum incanum cv. Marvelum, a large fruited autotetraploid produced from colchicine induced speciation (Anaso, 1989); Solanum gilo cv. Roundgreen, a diploid with medium sized

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POULTRY MANURE AND EGGPLANT YIELD 343

fruit; and Solanum gila cv. Sweet Samaru, another diploid with small sized fruit. All possible combinations of the three eggplant genotypes and five manure rates were laid out in randomized complete blocks with three replications. Each plot measured 1.8 m x 3.6 m. The nurseries were sown on 13th June and the seedlings transplanted on 19th July, 1990.

Experiment 3 had treatments similar to Experiment 2 but with larger plots measuring 3.6 m x 4 m. The seeds were sown in the nursery on 7th February and the seedlings transplanted into the field plots on 6th March, 1991.

Maintenance operations

The manures were thoroughly worked into the soil to incubate for 1 week before the seedlings were transplanted at a spacing of 60 em x 45 em. Hoe weeding was done twice in each case for Experiments 1 and 2, but three times for Experiment 3. To avoid excessive fruit damage anticipated from fruit boring insects under the prevailing weather conditions, insect control, at anthesis only, was with Vetox 85 (carbaryl as the active ingredient) at 4 g J- 1 of water for Experiments 1 and 2, and Nuvan 1000 EC (with dichlorvos as active ingredient) at 5 ml J-1 of water for Experiment 3.

Data collection

The poultry manures collected from different sources; Avutu (Experiment 1), Nsukka (Experiment 2) and Udi (Experiment 3), were chemically analyzed for N, P, K, Ca, Mg, Na, Fe, Zn and Cu. The eggplant 5th leaf (at 117 DAP) and fruit (at table maturity) were also analyzed for their elemental contents. N determination was by the semi-micro Kjeldahl method (Pearson, 1976). P was determined colorimetrically by the vanadomolybdate method (Barton, 1948) while, Ca, Mg, Na, Cu, Fe and Zn were determined by use of atomic absorption spectrophotometer according to the A.O.A.C. (1975) procedure. The effects of poultry manure on soil pH was measured 104 days after manure application (DAMA). Soil electrical conductivity was measured in Experiment 2 as outlined by U.S. Department of Agriculture (1965). Fruit was harvested at weekly intervals when table mature tender fruits were picked. Yield records were on number and weight of fruits produced. The data collected were subjected to analysis of variance according to the procedure for a randomized complete black design as outlined by Gomez & Gomez ( 1984 ).

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344 CAROL N. OPARA AND J.E. ASIEGBU

RESULTS

Data on soil chemical properties showed the experimental sites to be sandy clay loam (Table 1). The soils were low in N, P, K and organic matter, and were acidic. The elemental concentrations in the poultry manures varied with respect to sources (Table 2). Although all the poultry manures were from deep litter systems, the manure collected from Udi gave lower nutrient concentrations, especially P, K and Mg, than those collected from Avutu and Nsukka.

The Solanum cultivars did not affect soil pH or electrical conductivity. At 104 days after manure application (DAMA), poultry manure applied at 15 or 20 t ha-1 increased soil pH compared with no manure (Table 3). The soil electrical conductivity was not significantly influenced by the quantities of poultry manure used in the experiment.

In Experiment 1, the number of fruits harvested increased with successive increments in the rate of poultry manure, except at 20 compared with 15 t ha-1 (Table 4). Average weight per fruit was greater at all rates of manure

TABLE I

Soil physical and chemical properties of the sites of the experiments.

Experiments 2 3

Mechanical properties

Sand(%) 59.3 57.3 55.3 Clay(%) 32.7 32.7 34.7 Silt(%) 8.0 8.0 10.0 Textural class sclt scl sci

Chemical properties

Soil pH (in water) 5.0 4.9 4.1 Soil pH (in KCl) 4.5 4.0 3.5 Organic matter (%) 1.8 1.5 1.2 Total N (%) 0.09 0.07 0.06 Total P (mg kg-1) 13.8 15.0 12.5

Exchangeable cations (meq. 100 g soil- 1)

K 0.05 0.03 0.04 Ca 1.69 2.25 1.50 Mg 0.17 0.15 0.17 Na 0.08 0.10 0.09 Fe (ppm) 6.25 6.25 8.50 Cu (ppm) 18.75 11.00 22.50 Zn (ppm) 1.70 2.25 1.63

tscl = sandy clay loam.

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POULTRY MANURE AND EGGPLANT YIELD 345

TABLE 2

Elemental concentrations in poultry manures from different locations.

Experi- Source Date men! location collected N p K Ca Mg Na Fe Zn Cu

(% of dry matter) (mg kg-1)

I Avutu Jul. 1990 2.05 1.95 1.20 2.95 0.67 0.11 0.17 0.16 9.9 2 Nsukka May 1990 1.73 1.61 1.13 3.19 0.58 0.14 0.23 0.17 10.0 3 Udi Feb. 1991 1.32 1.12 0.53 3.95 0.33 0.18 0.19 0.15 7.3

Mean 1.70 1.56 0.95 3.36 0.53 0.14 0.20 0.16 9.1

TABLE 3

Effects of poultry manure rates on soil pH and on soil electrical conductivityt.

Soil pH

Experiment I Experiment 2 Experiment 3

0

4.3 5.0 3.9

5

4.4 5.2 4.0

Soil electrical conductivity (mmhos cm- 1)

Experiment 2 0.06 0.06

Manure rates (t ha- 1)

10 15

4.7 5.4 4.1

O.o?

4.8 5.4 4.4

0.06

tdata are mean of three eggplant varieties for Experiments 2 and 3.

20 LSDoos

4.8 0.4 5.6 0.5 4.3 0.4

O.o? NS

application than when no manure was applied, but did not differ significantly among rates of manure application. Fruit yield (t ha-1) was significantly increased by each successive incremental manure rate.

Except for 5 t h-1 compared with no manure in Experiment 2, incremental application of manure significantly increased the number of fruits harvested per plant up to the rate of 15 t ha-1 beyond which no further benefits were apparent (Table 5). On average, Sweet Samaru produced three to three and half times more fruits than Marvelum, and always more than twice the number produced by Roundgreen. Fruit number was significantly increased in Roundgreen at 15 t ha-1 compared with no manure; and with Sweet Samaru, it was increased at 10 t ha-1 manure compared with no manure. Fruit yield generally increased with increased rates of poultry manure up to 15 t ha-1• On average, Sweet Samaru and Roundgreen gave similar yields which were higher than that of Marve1um. Within eggplant genotypes, yield was increased at 10 t ha-1 manure rate compared with no manure and at 10 compared with 5 t ha-1 manure rate in Roundgreen; with Marvelum yield was increased at 10

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346 CAROL N. OPARA AND J.E. ASIEGBU

TABLE 4

Effects of poultry manure rates on fruit yield in Marvelum eggplant (Experiment I )t.

Manure rates (t ha-1)

0 5 10 15 20 LSDoo5

Number of fruits plant-' 17.7 30.1 36.7 45.8 50.3 6.1 Average weight of fruit (g) 31.0 37.3 39.1 39.3 41.2 5.2 Total fruit yield (t ha-1) 20.5 41.6 53.8 66.5 76.9 9.6

tOnly S. incanum var. Marvelum was used in this experiment.

TABLE 5

Effects of poultry manure rates and eggplant varieties on number of fruits per plant and on fruit yield in Experiments 2.

Manure rates (t ha- 1)

0 5 10 15 20 Mean

Number of fruits plane'

Roundgreen 52.4 79.2 93.3 127.9 126.2 95.9 Marvelum 37.8 49.3 74.6 68.0 79.3 61.8 Sweet Samaru 147.2 170.3 212.6 287.5 273.3 218.2 Mean 79.1 99.6 126.8 159.6 161.1 125.3

Fruit yield (t ha- 1)

Roundgreen 34.9 48.2 63.0 83.8 77.9 61.6 Marvelum 25.3 35.0 54.7 63.3 74.2 50.5 Sweet Samaru 43.0 43.1 59.5 82.9 92.8 64.3 Mean 34.4 42.1 59.1 76.7 81.6 58.8

Fruit number Fruit yield

LSD0 05 for two manure (M) means 29.7 8.6 LSD0.05 for two variety (V) means 23.0 6.7 LSD0 05 for two M x V means 51.5 15.0

compared with no manure or 5 t ha-1 manure rate; and with Sweet Samaru, it was increased at 10 compared with no manure or at 15 compared with 5 or 10 t ha-1 manure rate.

Experiment 3 was cut short by up to 6 weeks by severe insect attack and virus infestation, evidently from rather early field transplanting. Consequently, there were depressions of 63-80% for fruit number and 45-59% for fruit yield (t ha-1) compared with Experiment 2. However, the effects of manure and Solanum variety followed the same general trends as for Experiment 2, and therefore the data are not presented.

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POULTRY MANURE AND EGGPLANT YIELD 347

There was no significant quadratic response of eggplant fruit yield to poultry manure application within the range of 0 to 20 t ha-1 used, and the linear function between yield and manure rate proved most adequate for predicting yield in the various eggplant cultivars as summarized in Table 6.

Eggplant varieties did not vary markedly in most of the leaf and fruit elemental concentrations and so only the manure means have been summarized in Table 7. Poultry manure application increased the N and K concentrations in the 5th leaf but not in the fruit. The P in the leaf or fruit was not significantly influenced by manure rates. While Mg in leaf and fruit tended to increase with increased manuring, Zn tended to decrease, although statistical significance was not clearly established.

DISCUSSION

Although the poultry manures from the three locations were from deep litter systems, they varied considerably especially in their contents of N, P, K and Mg. The nutrient content of poultry manures or manure from any other animals are known to vary depending on such factors as animal feed, age and condition of the animal (Phillips, 1977), and on handling of the manure (Heleman, 1967). Other factors may have contributed to the variability in the present investigation. For example, because of the shortage and high cost of inorganic fertilizers, poultry manure has become a popular alternative, attracting high prices. Consequently poultry keepers make additional profits through more frequent removal and sale of the litter, often not allowing enough time for the droppings to accumulate. This practice varies with keepers and it will be

TABLE 6

Yield prediction equations based on poultry manure rates, and on a combination of number of fruits harvested per plant and weight per fruit in Experiments I and 2.

Use of manure rates in yield prediction

Experiment I

Marvelum

Experiment 2

Round green Marvel Sweet Samaru Mean of varieties

Y = -12.6473 + 0.36783X

Y = -9.6732 + 0.3896X Y = -11.4881 + 0.3344X Y = -11.4881 + 0.3344X Y = -12.1121 + 0.3762X

0.990*

0.945* 0.991 ** 0.966** 0.985**

Y = eggplant fruit yield (t ha- 1); X = manure rate (t ha- 1); * = p < 0.05; ** = p < 0.01.

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348 CAROL N. OPARA AND J.E. ASIEGBU

TABLE 7

Effect of poultry manure rates on eggplant leaf and fruit nutrient concentrationst in Experiment 2.

Manure rates Nutrient element 0 5 10 15 20 LSDoo5

5th leaf nutrient content (% dry matter)

N 4.15 4.34 4.47 4.53 4.59 0.27 p 0.36 0.34 0.31 0.32 0.35 NS K 5.36 6.29 5.53 7.31 7.81 2.30 Ca 1.08 !.II 0.97 1.04 1.18 NS Mg 0.31 0.33 0.35 0.35 0.33 NS Zn (ppm) 32.69 34.75 29.50 28.83 31.58 NS

Fruit nutrient content (% dry matter)

N 2.54 2.47 2.58 2.49 2.48 NS p 0.49 0.46 0.47 0.46 0.44 NS K 3.31 3.20 3.19 3.18 3.16 NS Ca 0.09 0.09 0.09 0.08 0.09 NS Mg 0.14 0.13 0.13 0.13 0.14 NS Zn (ppm) 21.25 18.00 19.00 17.72 17.43 3.49

t Analysis was done at 117 days after planting (peak vegetative phase) for the leaf and at table maturity for the fruit; and values are mean of three eggplant varieties.

helpful to buyers that at least the range of content of the major fertilizer elements in the manures should be known.

The increase in soil pH with poultry manure application was due to the relatively high content of Ca in the manures as also reported by Oikeh & Asiegbu (1993). The lack of effect of poultry manure application on soil electrical conductivity was partly due to the low content of salt in the manures and partly due to the relatively low quantities used. Shortall & Liebhardt (1975) found that the use of up to 56 t ha-1 of poultry manure that was also high in salt content resulted in levels of soil salinity detrimental to maize growth and yield.

The yield increases obtained with manure applications were essentially attributable to increases in the number of fruits harvested per plant as reported by Asiegbu & Uzo (1984) with farmyard manure, and to an increase in the average weight per fruit. However, application of organic manures is usually credited with improvements in soil chemical (Jackson eta!., 1975; Chattergee et a!., 1979; Mbagwu, 1992) and physical (Mbagwu & Ekwealor, (1990) characteristics, factors which are important for crop performance.

The manure rate of 15 t ha-1 appeared satisfactory for obtaining high eggplant fruit yields, although there was no significant quadratic response at the highest manure rate of 20 t ha- 1. However, in Experiment 1 there was a yield benefit at 20 compared with 15 t ha-1. Curve fitting always showed that

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POULTRY MANURE AND EGGPLANT YIELD 349

the linear functions gave the best relationship between fruit yield and manure application within the range of 0 to 20 t ha- 1. Oikeh & Asiegbu (1993), in a similar soil, recommended 15 to 17 t ha-1 as optimum for tomato production.

The individual highest yields of 76.9, 83.8 and 92.8 t ha-1 obtained for Marvelum, Roundgreen and Sweet Samaru, respectively, were satisfactory when compared with the yield of 23-50 t ha-1 obtained by Singh et al., (1985) for S. melongena in India. Field transplanting of Solanum very early in the season, in March, seemed undesirable as it was associated with serious insect pest attack and virus disease which, undoubtedly, led to yield depressions of 45 to 59% compared with transplants made in July.

Nutrient accumulation in the eggplant was not as dramatically increased as could be expected when inorganic fertilizer at comparable rates were applied (Asif & Greig, 1972). Also, the lack of, or low, effects of manure application on the leaf and fruit elemental concentrations might be in part attributed to possible dilution effect, whereby more of the nutrients absorbed with increasing manuring would have been used to produce more dry matter, thereby diluting the elemental concentrations. Ketiku et al. ( 1985) made a similar observation with Corchorus olitorus. Except for P and Mg, the concentrations of N, K, Ca, and Zn were lower in the fruit than in the leaf. A similar observation made with Ca by Carolus (1975) in tomato was attributed to reduced translocation across the abscission zone to the fruit.

ACKNOWLEDGEMENT

We thank the University of Nigeria, Nsukka, Nigeria!Katholieke Universiteit, Lueven, Belgium, Linkage Programme for financial support and for providing facilities for this work. The Linkage was funded from the European Development Fund (EDF) of the European Economic Community.

References

A.O.A.C. (1975). Official Methods of Analysis. 12th edn. Association of the Official Analytical Chemists; Washington D.C.

Anaso, H.U. (1989). Studies on induced speciation, manure rates, cytomorphology, and crossability in Solanum incanum complex. Ph.D. Thesis, University of Nigeria; Nsukka.

Asiegbu, J.E. & Uzo, J.O. (1984). Yield and yield component responses of vegetable crops to farmyard manure rates in the presence of inorganic fertilizer. Journal of Agriculture of University of Puerto Rico, LXVIII, 243-252.

Asif, M.l. & Greig, J.K. (1972). Effects of N, P and K fertilizers on fruit yield, macro- and micronutrients levels, and nitrate accumulation in okra (Abelmoschus esculentus (L.) Moench). Journal of American Society of Horticultural Science, 97, 440-442.

Barton, C.J. (1948). Photoelectric analysis of phosphate rocks. Analytical Chemistry, 20, 1068. Carolus, R. (1975). Calcium relationships in vegetable nutrition and quality. Communication in Soil

Science and Plant Analysis, 6, 285-298. Chattergee, B.N. & Singh, K.l., Pal, A. & Maiti, S. (1979). Organic manures substitutes for chemical

Dow

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fertilizers for high-yielding rice varieties. Indian Journal of Agricultural Science, 49, 188-192. Gomez, K.A. & Gomez, A.A. (1984). Statistical Procedures for Agricultural Research, 2nd edn.

John Wiley & Sons; New York. Heleman, L.H. ( 1967). The fertilizer value of broiler litter. Arkansas Experimental Station Bulletin,

159, 36. Jackson, W.A., Loenard, R.A. & Wilkinson, S.R. (1975). Land disposal of broiler litter-changes in

soil K, Ca and Mg. Journal of Environmental Quality, 4, 202-206. Ketiku, A.O., Kogbe, J.O.S. & Omololu, A. (1985). Studies on the manurial requirements of

Nigerian local leafy vegetables. I. Effects of poultry manure on the nutrient composition of the leaves of amaranthus and bush okra, Nigerian Agricultural Journal, 19/20, 136--144.

Mbagwu, J.S.C. (1989). Influence of irrigation frequency and mulching on the productivity of an Ultisol in southern Nigeria. I. Cowpea performance. Nigerian Agricultural Journal, 24, 21-31.

Mbagwu, J.S.C. (1992). Improving the productivity of a degraded Ultisol in Nigeria using organic and inorganic amendments. Part I: Chemical properties and maize yield. Bioresource Technology, 42, 149-154.

Mbagwu, J.S.C. & Ekwealor, G. C. (1990). Agronomic potential of brewers' spent grains. Biological Wastes, 34, 335-347.

Oikeh S.O. & Asiegbu, J.E. (1993). Growth and yield responses of tomatoes to sources and rates of organic manures in ferralitic soils. Bioresource Technology, 45, 21-25.

Pearson, D. (1976). The Chemical Analyis of Foods. Churchill Livingstone; London. Phillips, T.A. (1977). Agricultural Notebook. Longman; London. Shortall, J.G. & Liebhardt, W.C. (1975). Yield and growth of corn as affected by poultry manure.

Journal of Environmental Quality, 4, 186-191. Singh, J., Kashyap, R. & Shrivastava, S.S. (1985). Brinjal- promising varieties for Madhya Pradesh.

Indian Horticulture, 30, 14-15. Unamba-Oparah, I. (1985). The potassium status of the sandy soils of northern Imo State, Nigeria.

Soil Science, 139, 437-445. U.S. Department of Agriculture (1965). Agriculture Handbook 60, U.S. Department of Agriculture.

(Received 21st July, 1994; accepted 8th August, 1995)

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