Organic Food Chain Management - Uni Hohenheim · PDF fileScheme of a dicotyledonous plant in vegetative state ... and transport (like sugar) or plant organic matter for ... - many

Tutorial

Organic Food Chain Management

Basics of Crop Production

Institute for Crop Production and Grassland Research Prof. Dr. W. Claupein

compiled by Jens Poetsch (November 2006)

Contents

A Basics of Botany

A.1 Taxonomy of higher plants

A.2 Plant morphology

A.3 Plant physiology

A.4 Usable plant parts

A.5 Checkup, references and further reading

B Basics of Soil Science

B.1 Soil genesis and nutrient cycling

B.2 Soil characterisation

B.3 Particles, texture, structure, air and water regime

B.4 Checkup, references and further reading

C Agricultural Crops

C.1 Cereals (starch crops)

C.2 Protein crops

C.3 Oil crops

C.4 Root and tuber Crops

C.5 Important tropical crops

C.6 Arable fodder cropping

C.7 Grassland

C.8 Renewable raw materials

C.9 Checkup, references and further reading

D Crop Management

D.1 Crop life cycle and site adaption

D.2 Crop rotation

D.3 Soil cultivation

D.4 Sowing

D.5 Harvest

D.6 Checkup, references and further reading

E Plant Nutrition and Fertilization

E.1 Plant nutrients

E.2 Fertilization

E.3 Nitrogen cycle

E.4 Checkup, references and further reading

F Weed Management

F.1 Weed biology

F.2 Weed control

F.3 Checkup, references and further reading

Important Crops and Weeds

Units and Abbreviations

Index

A Basics of Botany

A.1–1

A Basics of Botany

A.1 Taxonomy of higher plants

� The kingdom of plants is hierarchically structured in division, class, order, family, genus and species, describing higher or lesser degress of relationship. Two ex-amples for worldwide important crops are:

wheat (Triticum aestivum) soybean (Glycine max)

division seed-bearing plants (Magnoliophyta)

class monocotyledons (Liliopsida) dicotyledons (Magnoliopsida)

order (Poales) (Fabales)

family true grasses (Poaceae) legumes (Fabaceae)

genus wheat (Triticum) (Glycine)

species bread wheat (T. aestivum) soybean (G. max)

� The scientific name of a plant, like e.g. Triticum aestivum for wheat, complies with genus (Triticum) and species (aestivum).

� Species are further divided in forms and cultivars (= varieties): - forms may be the result of evolution or breeding; they describe strongly differing genetic types within a species (like growth habit or site adaption) - cultivars are the result of breeding activities and usually have closely defined ag-ronomic properties

� Almost all usable plants belong to the division of seed-bearing (“higher”) plants. The lower divisions of ferns, mosses and algae only have specialized uses. (Fungi are not plants but a separate kingdom.)

� Agriculturally important classes are the Monocotyledons (including grain and fod-der grasses, onions, orchids, palm trees) and Dicotyledons (including most de-ciduous trees, legumes and other herbaceous plants).

� Cotyledons are the seed-leaves, the first leaves of a plantlet, already embodied in the seed. The number (one or two) of cotyledons is one distinctive feature of mono- and dicotyledonous plants. Many other features account for important dif-ferences in cultivation.

A Basics of Botany

A.1–2

Franke, 1997

Monocotyledonous plantlet (onion)

Dicotyledonous plantlet (mustard)

Cotyledons

Primary root

A Basics of Botany

A.2–3

A.2 Plant morphology

� A higher plant consists of three basic parts: stem, root and leaves

� The stem is divided by nodes. Each node can produce one or more leaves. The axil of each leave contains a bud that may become a secondary stem.

� The terminal buds are the parts where growth continues. Additionally, the inter-nodes (the parts between nodes) are able to elongate, increasing plant height.

� In the root hair zone most water and nutrients are absorbed. Larger (older) roots are important for stability and transmittance of water and nutrients into the above-ground plant parts.

� The inflorescence (the part bearing the flowers) is not a discrete plant organ but a specialized part of stem and leaves that also originates from buds.

Scheme of a dicotyledonous plant in vegetative state(Franke, 1997)

cotyledons

root hair zone

primary root

secondary root

main stem

node

internode

accessory bud

leaf

terminal buds

secondary stem

A Basics of Botany

A.2–4

raceme ear cob umbel

composite raceme composite ear

Examples for different inflorescences(Franke, 1997)

raceme ear cob umbel

composite raceme composite ear

Examples for different inflorescences(Franke, 1997)

� Simple inflorescences have an axis with flowers. Composite inflorescences have an additional branching structure.

� The inflorescence e.g. of wheat (Triticum aestivum), rye (Secale cereale) and bar-ley (Hordeum vulgare) is a composite ear (only packed closer than in the picture).

� The inflorescence of oat (Avena sativa) is a composite raceme (also called pani-cle).

� Other examples for inflorescences are rapeseed (Brassica napus: raceme), maize (Zea mays: cob), fennel (Foeniculum vulgare: umbel).

A Basics of Botany

A.3–5

A.3 Plant physiology

� For optimum growth plants need: warmth, water, nutrients, light and air.

� Water is taken up from the soil and conducted upwards where it is finally tran-spired through the leaves. This upward flow carries nutrients from the soil to the plant parts where they are needed.

� Water use efficiency of crops may differ. As is shown in Fig. 5.12 durum wheat (Triticum durum) may produce acceptable yields at low water supply, but bread wheat (T. aestivum) profits more (steeper line) from additional water. Table 11.13 shows examples of total water consumption by some crops in one cropping sea-son.

� Note: “evapotranspiration” specifies the sum of direct evaporation from the soil and transpiration through the plant. Millimeters (mm) as a unit for precipitation or evapotranspiration are equal to litres per m2, because pouring one litre of water on the area of one m2 makes a pond of one mm depth.

in: Pratley, 2003

A Basics of Botany

A.3–6

Pratley, 2003

� Sunlight is intercepted by plants, and a part of its energy is transformed to chemi-cal energy in a process called photosynthesis. The energy is used to split aerial carbondioxide (CO2) into carbon (C) and oxygen (O2).

� Carbon is finally used to produce substances (“assimilates”) for energy storage and transport (like sugar) or plant organic matter for growth.

� There are two important biochemical energy-pathways. According to the number of carbon atoms in the determining intermediate product they are called C3- and C4-pathway.

� If all other growth factors are abundant, growth of C3-plants is limited by CO2-supply from the air. A further increasing light intensity can not be used by the plants. Current CO2-content of the air is 380 ppm (= 0,038%, increasing through fossil energy use).

� C4-plants are more efficient in taking CO2 from the air and can make use of high light intensities, where CO2-supply is not a limiting factor for them.

� C3-plants are more efficient in converting light energy. At low light intensities C3-plants have a higher photosynthesis rate than C4-plants. Moreover, C3-plants still grow at low temperatures, while C4 plants need warmer climates.

� In conclusion, most C4-plants originate from low latitudes (tropics and subtropics) with high light intensity. Important C4-plants are maize, sugar cane, sorghum.

� At higher latitude (north and south) C3-plants like wheat or rapeseed are more widespread, but rize, bean and many other crops also are C3-plants.

A Basics of Botany

A.3–7

photosynthesis rate(dry matter assimilation)

light intensity

shade adapted C3-plants

sunlight adapted C3-plants

C4-plants(always sunlight adapted)

Linder, 1989

C3-plants more efficient � � C4-plants more efficient


light intensity




Linder, 1989


light intensity




Linder, 1989

C3-plants more efficient � � C4-plants more efficient

� Shade adapted plants are particularly efficient at low light intensity, but their maximum growth rate is strongly limited.

� Better CO2 supply or efficiency also reduces water transpiration, because the plant requires less air exchange. Thus, C4-plants are more water efficient than C3-plants.

� Air also contains oxygen (21%). To use the energy stored by photosynthesis, plants need oxygen to breathe. The roots, in the absence of light energy, are de-pendent on assimilates from the upper plant parts and oxygen in the soil air.

Impact of CO2 concentration (318 vs 671 ppm) on plant physiological parameters of spring wheat (Manderscheid et al, 1999)

CO2

Parameter normal enriched effect (%)

absorbed radiation (MJ/m2) 414 413 - 0,4evapotranspiration (mm) 292 225 - 14,8dry matter (g/m2) 1919 2083 + 8,5

in: Diepenbrock et al, 2005


CO2




CO2



in: Diepenbrock et al, 2005

A Basics of Botany

A.3–8

� After a period of vegetative growth most plants change to the generative stage: producing flowers and eventually seeds.

� Depending on the desired product, harvest may take place before flowering (e.g. sugar beet, lettuce, asparagus).

� In addition to producing seeds (generative propagation) many plants are able to produce new plants from parts of themselves (vegetative propagation) - examples are potatoe (tubers) or several weeds (thistle, couch grass).

� Often seeds are the harvest product. For optimum propagation the plant concen-trates energy (starch, oil), protein and other nutrients in the seed, which makes it a valuable food object.

� To make sure that flowering and seed production take place in a favourable sea-son (temperature in colder climates, water supply in monsoon climates) plants have different mechanisms. - they can perceive day length: if days are too short or too long (depending on the plant’s origin) the plant may not flower at all - many plants have a “frost security system”: they will not flower before a certain period of low temperatures has passed, the process being called “vernalization” � These mechanisms may affect site suitability and optimum sowing date

A Basics of Botany

A.4–9

A.4 Usable plant parts

� Basically all plant parts can be used.

� Seeds of many crops have particularly high contents of special substances like starch (cereals), protein (beans, peas) or oil (rapeseed, sunflower).

� Fruits are the casing of developing seeds. At harvest they may be a mere con-tainer (like dry pods) or a store for additional nutrients and water (fruits and vege-tables).

Bickel-Sandkötter, 2001

pod and seed of common bean

(Phaseolus vulgaris)open pod with septum and

seeds of oilseed rape(Brassica napus)

berry cross-section oftomato

(Solanum lycopersicum)


pod and seed of common bean

(Phaseolus vulgaris)open pod with septum and

seeds of oilseed rape(Brassica napus)

berry cross-section oftomato

(Solanum lycopersicum)

� Other desirable harvest products are not related to seed production but to energy storage of the plant.

� For storing large amounts of assimilates, plants may develop expanded root or stem parts. Examples are turnips, carrot, swede. The sugar beet (Beta vulgaris) contains high amounts of sugar as energy store. The potato tuber (Solanum tube-rosum) serves simultaneously as energy store and propagation unit. A stem that contains large amounts of sugar is the sugar cane (Saccharum officinarum).

� Other plant stems may be harvested for their good fibre characteristics, like hemp (Cannabis sativa) or linen resp. flax (Linum usitatissimum).

� Even inflorescences are edible harvest products. Cauliflower is an extremely ex-panded inflorescence.

� Whole plants (aboveground, without roots) are harvested for animal feeding (hay or green fodder) or energy purposes (burning).

� Some plants may be used for diverse purposes by specialized breeding; for ex-ample rape-seed and swede are of the same species (Brassica napus).

A Basics of Botany

A.4–10

(Bickel-Sandkötter, 2001)

swede cauliflower sugarcane(Brassica napus) (Brassica oleracea) (Saccharum officinarum)

(Bickel-Sandkötter, 2001)

swede cauliflower sugarcane(Brassica napus) (Brassica oleracea) (Saccharum officinarum)

A Basics of Botany

A.5–11

A.5 Checkup, references and further reading

� What are the basic parts of a higher plant?

� What is an inflorescence?

� What are the major requirements for plant growth?

� What is photosynthesis?

� What is evapotranspiration, and how is it linked to plant growth and CO 2 supply or efficiency of a plant?

� What is the difference between C3 and C4-plants?

� Which plant parts are usable, and what are their ma jor contents?

References

BICKEL-SANDKÖTTER, S., 2001: Nutzpflanzen und ihre Inhaltsstoffe. Quelle und Meyer, Wie-belsheim

DIEPENBROCK, W.; ELLMER, F.; LÉON, J., 2005: Ackerbau, Pflanzenbau und Pflanzenzüch-tung. Grundwissen Bachelor, Ulmer, Stuttgart

FRANKE, W., 1997: Nutzpflanzenkunde - Nutzbare Gewächse der gemäßigten Beiten, Subtro-pen und Tropen. 6., neubearb. u. erw. Aufl., Thieme, Stuttgart

LINDER, H., 1989: Biologie - Lehrbuch für die Oberstufe. 20., neubearbeitete Auflage, von H. Bayrhuber, U. Kull, U. Bäßler, A. Danzer, Metzler, Stuttgart

PRATLEY, J. (Ed.), 2003: Principles of field crop production. 4th edition, Oxford University Press, Melbourne

Further reading

EVANS, L.T., 1996: Crop Evolution, Adaptation and Yield. Cambridge Univ. Press, Cam-bridge, UK

PESSARAKLI, M. (Ed.), 2002: Handbook of Plant and Crop Physiology. Marcel Dekker, Inc., New York, Basel, Hong Kong


B.1–1


B.1 Soil genesis and nutrient cycling

http://ic.ucsc.edu

� Soil is an ecosystem at the interface of lithosphere, atmosphere, hydrosphere and biosphere.

� Essential soil forming processes are physical and chemical weathering of rock parent material and cumulative enrichment with dead and living organic matter. Thus, the solid part of a soil consists basically of minerals and humus.

� Air and water filled pores in the soil are essential for the survival of plant roots, soil inhabiting animals and microorganisms.

� Soil is also a production factor for agriculture. A fertile soil is characterized by a balanced supply of plant nutrients, good water storage capacity, sufficient aeration and high biological activity.

� Plant and animal residues are subject to microbal decomposition in a process called mineralization. Nutrients fixed in organic matter become (again) available for root uptake by plants through mineralization.

� Stable organic compounds in the decomposition process are transformed to hu-mus and important for a good soil structure.


B.2–2

B.2 Soil characterisation

Ashman & Puri, 2002

� The formation of different soil types depends on environmental variables such as climate, parent material, organisms, topography and time.

� According to the major processes in different depths, a soil can be divided in hori-zons which are often clearly visible in a vertical soil profile. This profile defines the soil type.

� The predominant part of agricultural activities takes place in the A horizon (20-30 cm). Deeper horizons are also penetrated by roots and add significantly to plant available water and nutrients.


B.3–3

B.3 Particles, texture, structure, air and water regime

Ashman & Puri, 2002

� Depending on parent material and soil formation history the particle size of a soil will differ. Sand feels granulous, dry silt feels like flour, and clay is kneadable when moist or hard when dry. Particles > 2 mm are referred to as gravel.

� The proportion of sand, silt and clay in a soil is referred to as its soil texture. The second term (as in “loamy sand”) describes the main character, the first term an additional tendency.

� Loam is a term for soil types, consisting to a fair degree of all three fractions.

� Additionally, soils contain organic compounds, referred to as humus. Typical hu-mus contents of agricultural soils are 1% to 5% by weight.


B.3–4

Ashman & Puri, 2002

� Mineral particles and organic compounds from microbes, plant roots and animals form aggregates referred to as crumbs.

� Crumbs improve a soil’s structure and stability against compaction (elasticity ef-fect) or crustification, and have a high water-holding capacity (sponge effect).

� Earthworm castings are stable and nutrient rich crumbs.


B.3–5

Ashman & Puri, 2002

Ashman & Puri, 2002

� 45-50% of soil volume consists of pores. Pore-size depends on soil texture and structure. Macropores will drain quickly (transmission). Meso- and micropores hold water through capillarity, but water in micropores is held too tight for plants to be available (residual water).

� Macropores are important for soil aeration and growth of plant roots. Mesopores are important for plant water supply.

� Pore volume and pore-size distribution may be affected by soil compaction (e.g. caused by cultivation). A good soil structure prevents compaction. Soils with a weak structure may even be compacted by heavy rain and gravity.


B.3–6

Ashman & Puri, 2002

� The tension at which water is held by capillarity is measured in MPa. For a specific soil there is a definite correlation between water content and tension, which can be shown in a moisture release curve.

� There are two important points on the moisture release curve. At the permanent wilting point there is only plant unavailable water (micropores) left in the soil. At field capacity there is as much water stored in the soil as possible (only macro-pores remain air-filled). Each additional amount of water will drain quickly.

� The water content between these points is referred to as plant-available water. The soil volume corresponding to plant-available water can be read as the hori-zontal difference of water contents at PWP and FC.

� The total amount of plant available water is determined by percentage of soil vol-ume and depth of root penetrable soil. Typical magnitudes are 100 to 250 l/m2. (for comparison: average annual precipitation in Germany: 600-900 l/m2).

� Note: Precipitation in litres per m2 can also be measured in mm, because pouring one litre of water on the area of one m2 makes a pond of one mm depth.

� Soil aeration depends on soil texture and moisture. While macropores are usually filled by air, mesopores may be filled by either air or water.


B.4–7

B.4 Checkup, references and further reading

� Why is an unbalanced precipitation (e.g. wet spring and dry summer) more adverse for crop water supply on sandy soil than on loamy soil?

� Why does a clay soil store less plant-available wat er than loam, although it contains more water in total?

� What are the benefits of high biological soil activ ity for soil structure?

� What are the characteristics of a fertile soil? How could different parame-ters be improved?

References

ASHMAN, M.R.; PURI, G., 2002: Essential Soil Science - a clear and concise introduction to soil science. Blackwell, Oxford Berlin

Further reading



B.4–1


� The basic aim of agricultural activities is harvesting a high yield.

� Yield is commonly indicated by weight per area. Typical units are t (tonne) or Mg (Megagramme = 106 gramme = 1 t) per ha (hectare). 10 t/ha equal 1 kg/m2

� In Germany the weight unit dt (decitonne = 0,1 t = 100 kg) is common. In the USA yield is measured in bushel (US bush.) which is a unit of volume, but for each crop there is a defined weight for one bushel, e.g. 1 bushel wheat = 27,2 kg and 1 bushel maize = 25,4 kg. The area also may be measured in different units, like the chinese Mu (= 1/15 ha) or the american acre (= 4046,9 m2).

� Yield may be refering to dry matter (DM, as a measure for actual growth efficiency and accumulated sunlight) or fresh matter (including variable amounts of water).

� Commonly, yield of grain crops is given at a uniform moisture content, e.g. of 14% (= 86% DM) which represents the standard storage condition.

� Yield of root and tuber crops is commonly given as fresh matter. For sugar beet it may be given as sugar yield.


C.1–2

C.1 Cereals (starch crops)

� Cereals belong to the family of grasses (Poaceae) and are grown as staple foods worldwide. They contain starch (=energy), protein (8-15%), minerals and further favourable substances. Cereals are consumed as bread, pasta, cooked or as mush.

� Of high worldwide importance, depending on climate, are wheat, rice and maize.

� Important cereals grown in temperate climates are wheat, rye, barley and oat. Wheat, rye and barley produce ears (= spikes), while the inflorescence of oat is called panicle. The ears of rye and barley have awns, usually longer in barley than in rye.


Wheat Rye Barley Oat(Triticum (Secale (Hordeum (Avenaaestivum) cereale) vulgare) sativa)

awns


Wheat Rye Barley Oat(Triticum (Secale (Hordeum (Avenaaestivum) cereale) vulgare) sativa)

awns


C.1–3

� Maize is a C4-plant of high productivity.

� Maize produces separate male and female inflorescences. The female inflores-cence is a cob (1-2 per plant) and finally bears the yield.

� In colder climates maize may not always reach maturity but can also be grown as a highly productive green fodder crop.

Maize(Zea mays)

female inflorescences

(silt)


male inflorescence(tassel)

Cob

styles of female flowers

Maize(Zea mays)

female inflorescences

(silt)


male inflorescence(tassel)

Cob

styles of female flowers


C.2–4

C.2 Protein crops

� Plants belonging to the family of legumes (Leguminosae) and producing seeds with a protein content of 20-45% are referred to as proteincrops. They are used for protein nutrition of humans and animals.

� The seeds are usually harvested dry when pods open easily and seeds are stor-able. Alternatively, unripe (green) pods of some protein crops may be harvested as vegetable (pea, garden bean).

� Important protein crops in Europe are field pea and field bean.

� The pea uses tendrils (parts of the leaves) to get a hold on other plants.

Bickel-Sandkötter, 2001 www.botanical-online.com

Field pea Field bean(Pisum sativum) (Vicia faba)

climbing not climbing

flowers

pods

tendrils

Bickel-Sandkötter, 2001 www.botanical-online.com

Field pea Field bean(Pisum sativum) (Vicia faba)

climbing not climbing

flowers

pods

tendrils


C.2–5

� In warmer climates soybean and common bean are grown.

� The common bean has a large diversity of forms, from runner beans (long green pods used as vegetable) to kidney beans or black beans.

� Soybean is by far the most important protein crop worldwide. It contains approx. 20% oil and 40% protein. For this reason it is also grown as an oil crop.

� A common feature of all legumes (comprising protein crops and fodder legumes) is the formation of root nodules. These give the crops an important advantage in ni-trogen supply. Nitrogen is an essential element for plant growth in general and protein production in particular.

Bickel-Sandkötter, 2001 Brücher, 1977

Soybean Common Bean(Glycine max) (Phaseolus vulgaris)

pods

root nodules

Bickel-Sandkötter, 2001 Brücher, 1977

Soybean Common Bean(Glycine max) (Phaseolus vulgaris)

pods

root nodules


C.3–6

C.3 Oil crops

� Vegetable oil can be extruded from seeds rich in oil. Typical oil contents of those seeds are between 30 and 50%.

� Examples for oil seed crops are sunflower and rapeseed.

� Vegetable oils have a higher nutritional value than animal fats.

� There are also “non-food” (technical) uses for vegetable oils. One is the production of biodiesel from rapeseed-oil.

� High oil contents may also be found in fruits (olives, palm-oil).

Bickel-Sandkötter, 2001 http://bitininkas.tinklapis.lt

Sunflower Rapeseed(Helianthus annuus) (Brassica napus)

Bickel-Sandkötter, 2001 http://bitininkas.tinklapis.lt

Sunflower Rapeseed(Helianthus annuus) (Brassica napus)


C.4–7

C.4 Root and tuber Crops

� Many crops are grown for subterranean products like turnips, beets or tubers.

� The potatoe is planted as a seed potato. From this tuber a whole plant evolves, producing a stem and leaves, roots and new tubers. While the seed potatoe is consumed in the process, new tubers can be harvested from the soil. The above-ground plant can not be used.

Potato plant(Solanum tuberosum)

Seed potatoe (= old “mother” tuber)

Potatoe tuber

Poisonous potatoe berry

flower

Potato plant(Solanum tuberosum)

Seed potatoe (= old “mother” tuber)

Potatoe tuber

Poisonous potatoe berry

flower


C.4–8

� Turnips and beets are expanded roots (and lower parts of the stem), storing en-ergy and other substances. In contrast to the potato they do not store energy for propagation but for endurance.

� Usually flowering is undesirable, because part of the stored substances would be consumed for producing flower and seeds. So the crop must be harvested when the maximum storage is reached.

� An example of diverse forms of one species is Beta vulgaris: - the sugar beet stores approx. 18% by weight of sugar in its root - the forage beet produces less sugar, but has a high productivity as fodder crop - the beetroot produces purple-red roots that are used as vegetable - another form of Beta vulgaris is grown for its leaves as vegetable and called chard or leaf beet; it has almost no beet


cultivated forms of Beta vulgaris:

sugarbeet (A), forage beet (B), beetroot (C), chard/leaf beet (D)

D


cultivated forms of Beta vulgaris:

sugarbeet (A), forage beet (B), beetroot (C), chard/leaf beet (D)

D


C.5–9

C.5 Important tropical crops

� Many other crops produce spices, luxury foodstuffs and other commodities.

� Coffee originates in Africa and is today an important export product of middle and south america. The fruit contains two seeds that are fermented, roasted and milled to produce the well known hot beverage.

Coffee plant

berry bean

Coffee plant

berry bean


C.6–10

C.6 Arable fodder cropping

� Green fodder plants can be grown on arable land. Usually the aboveground plant matter is harvested 3-5 times a year. Total use over a period of two years is com-mon.

� Most important groups of arable fodder crops are legumes and grasses.

� Legumes, like red clover, have a high feeding value and protein content.

� Grasses, like annual ryegrass, have a high productivity and better storage suitabil-ity than legumes.

� Growing of mixtures (“grass clover”) of two or more species for arable fodder pro-duction is very common. Mixtures have a higher productivity than monocultures, and good storage and fodder qualities.

� Arable fodder cropping improves soil structure and reduces weed pressure.

www.fk.noFrame, Charlton, Laidlaw, 1998

Red clover Annual ryegrass(Trifolium pratense) (Lolium multiflorum)

www.fk.noFrame, Charlton, Laidlaw, 1998

Red clover Annual ryegrass(Trifolium pratense) (Lolium multiflorum)


C.7–11

C.7 Grassland

� Usually grassland is cultivated on sites not suited for arable farming, because of bad soil water conditions (too wet or too dry), risk of erosion, low fertility and other reasons.

� The term grassland describes plant societies of grasses, legumes and other her-baceous plants, used as - pasture (for grazing of animals) or - meadow (harvesting of green fodder for storage or feeding in the stable)

� The agricultural difference between grassland and arable fodder cropping over several years may be small.


C.8–12

C.8 Renewable raw materials

� Important non-food uses for plant materials are fibre and energy production (in-cluding oil crops).

� Hemp is a plant producing edible seeds, fibre (stem) and pharmaceuticals (flower). Hemp fibre - like many plant fibres - can be used for textiles and technical pur-poses.

� All plants or plant residues can be used for energy production. A specialized way of “energy cropping” is the growing of so-called short rotation coppice. Fast grow-ing trees, like the willow, are cut every 3-4 years for fuelwood production. Suitable species can easily grow new shoots over a long period.

Hemp WillowHemp Willow


C.9–13

C.9 Checkup, references and further reading

� Name some important crops for energy and protein su pply in human nutri-tion.

� What do cereals, protein crops and oilseeds have in common, concerning agricultural production?

� How could harvest of potatoes be accomplished mecha nically?

� When should beets and turnips be harvested?

� What non-food uses of plants do you know?

� What are the typical crops and production methods o f green fodder?

References

BICKEL-SANDKÖTTER, S., 2001: Nutzpflanzen und ihre Inhaltsstoffe. Quelle und Meyer, Wie-belsheim

FRAME, J.; CHARLTON, J.F.L.; LAIDLAW , A.S., 1998: Temperate forage legumes. Wallingford, CAB International

Further reading

MCMAHON, M.J.; KOFRANEK, A.M.; RUBATZKY , V.E., 2006: Hartmann's plant science : growth, development, and utilization of cultivated plants. Upper Saddle River, NJ : Pearson Prentice Hall

D Crop Management

D.1–1

D Crop Management

D.1 Crop life cycle and site adaption

� A typical arable crop is annual, meaning that the vegetative period between sow-ing and harvesting is one year or less.

� In temperate climates there are spring-sown and autumn-sown crops.

� Spring-sown crops are sown after winter when the temperature required for the respective crop is reached.

� Autumn-sown crops are sown before winter and achieve a certain pre-development. They have to endure the cold season, but in spring they have a headstart on spring-sown crops. Due to their longer vegetative period in total they have a higher yield potential.

� All crops can be sown in spring. Additionally there are cultivars of several crops with sufficient cold tolerance for autumn-sowing. It is important that they do not develop flowers before winter, because these would not survive. This is achieved by a plant mechanism called vernalization: the production of flowers is blocked un-til the plant has received a sufficient cold stimulus.

� Typical autumn-sown crops in Germany are winter wheat (Triticum aestivum), win-ter barley (Hordeum vulgare), winter rye (Secale cereale) and winter rapeseed (Brassica napus).

� Harvest of autumn- and spring-sown crops takes place from summer until early autumn, depending more on species than on sowing time.

� Perennial crops, used for more than one year (e.g. forage crops), may be sown in favourable conditions, but then have to survive all seasons.

� Besides climate, soil conditions have a strong impact on cropping suitability.

D Crop Management

D.2–2

D.2 Crop rotation

� A crop rotation is a sequence of different crops that is repeated in a cycle of sev-eral years.

� A “crop rotation” of one year, meaning that the same crop is grown on one field over and over, is called monoculture. Typical impacts of this crop, like promotion of specific pests or depriving of certain nutrients can accumulate.

� Alternating crops reduces these problems and provides advantages like growing nutrient demanding crops after nutrient mobilising crops, weed sensitive crops af-ter weed competitive crops etc.

� Typical crop rotations have a cycle of 3-4 years in conventional farming or 6-8 years in organic farming. An exemplary 7 year rotation in organic farming may be: 2 years grass clover, winter wheat, potatoes, spring barley, field pea, winter rye

� To have a constant farm output every year, the arable area must be divided equally to the years of the crop rotation. In the example a 70 ha farm may have 7 fields of 10 ha. Each field is cropped with another rotation member. Two fields will be cropped with grass clover (one in the first, one in the second year).

Example of a 4-year crop rotation

year field 1 field 2 field 3 field 4

2005 sugar beet winter wheat winter barley oats

2006 oats sugar beet winter wheat winter barley

2007 winter barley oats sugar beet winter wheat

2008 winter wheat winter barley oats sugar beet

2009 same as 2005

D Crop Management

D.2–3

Pratley, 2003

D Crop Management

D.3–4

D.3 Soil cultivation

Diepenbrock, Ellmer, Léon, 2005

historic tools for soil cultivation

Diepenbrock, Ellmer, Léon, 2005

historic tools for soil cultivation

� Major aims of soil cultivation are: loosening of the soil, incorporation of organic residues, weed suppression, optimizing conditions for sowing.

� Cropping may compact the soil and decrease root permeability. Frequent loosen-ing of the soil is recommended.

� The most common system in Germany is the mouldboard plough. Bars of soil are cut and turned for about 3/8 of a rotation (135°).

� By “throwing” the soil it is fractured into natural crumbs with a good loosening ef-fect. Organic residues and weeds are worked into the soil.

� The new surface is relatively “clean” soil that is well suited for seedbed prepara-tion.

� Turning too much soil has negative effects on soil organisms.

� A common rule for organic agriculture is: “turn shallowly, loosen deeply”

D Crop Management

D.3–5

Ashman & Puri, 2002

Schön, 1998

furrow

plough bar

turn-over angle

Schön, 1998

furrow

plough bar

turn-over angle

� The picture below shows three basic soil cultivation systems.

D Crop Management

D.3–6

bare soil

“plough pan”(subsoil compaction)

untilled subsoil

organic residues

tractor-cultivator

continuous change from tilled

to untilled soil

organic residues worked in shallowly

rotary directsowing

organic residuesat soil surface


to untilled soil

basic soil management systems (Schön, 1998)

soil-turning tillage

soil-loosening tillage

no tillage

no mulch cover

mulch cover

mulch cover

bare soil

“plough pan”(subsoil compaction)

untilled subsoil

organic residues

tractor-cultivator


to untilled soil

organic residues worked in shallowly

rotary directsowing

organic residuesat soil surface


to untilled soil

basic soil management systems (Schön, 1998)

soil-turning tillage

soil-loosening tillage

no tillage

no mulch cover

mulch cover

mulch cover

D Crop Management

D.4–7

D.4 Sowing

ideal seed bed resp. plant bed for different crops(Sommer, 1997)

rapeseed wheat pea field bean potatoe

loose soil cover

recompacted soil

mellowtilled layer

subsoil

seed

bed

prep

arat

ion

tilla

ge

water

ideal seed bed resp. plant bed for different crops(Sommer, 1997)

rapeseed wheat pea field bean potatoe

loose soil cover

recompacted soil

mellowtilled layer

subsoil

seed

bed

prep

arat

ion

tilla

ge

water

� An ideal seedbed should provide an even, loose soil cover that quickly increases in temperature and permits air to the seed. Recompacted soil below the seed pro-vides sufficient capillarity to conduct water from the soil to the seed.

� Tools like the harrow produce a level, well-crumbled seed bed.

� Larger lumps of soil can be broken by a roller which also provides recompaction for capillarity and water conduction.

Schön, 1998

www.ralle-landmaschinen.de

harrow crumbling roller

Schön, 1998

www.ralle-landmaschinen.de

harrow crumbling roller

D Crop Management

D.4–8

rotary hoe circular harrow reciprocating harrow

PTO shaft powered tools (Schön, 1998)

rotary hoe circular harrow reciprocating harrow

PTO shaft powered tools (Schön, 1998)

� Modern tractors provide a PTO (“power-take-off”) shaft: a turning axis, powered by the tractor engine, suitable to attach tools that have a stronger working effect on the soil. This may be required on heavy soils or if loosening has not been suffi-cient.

seed distribution

sowing machine

seed container

sowing tine

support/drive wheel

sowing harrow

seed distribution

sowing machine

seed container

sowing tine

support/drive wheel

sowing harrow

Schön, 1998

D Crop Management

D.5–9

D.5 Harvest

� Grain crops can be harvested very efficiently by a combine harvester. This ma-chine - cuts the crop and feeds it in - threshes the crop, to get the seeds from ears or pods - separates seeds from straw and husks by sieves and wind

Pratley, 2003 (adapted from Kepner et al, 1982)

historical

sieving threshing cuttingunit unit unit

Pratley, 2003 (adapted from Kepner et al, 1982)

historical

sieving threshing cuttingunit unit unit

D Crop Management

D.6–10

D.6 Checkup, references and further reading

� What are annual and perennial crops?

� What is autumn-sowing and what are its advantages a nd conditions?

� What is a crop rotation, and what are its benefits?

� What are the aims of soil cultivation?

� Name three basic soil management systems. How well or not can they achieve the aims of soil cultivation?

� What are the characteristics of an ideal seedbed?

� What is the meaning of dry matter yield, fresh matt er yield and yield at 86% DM?

� What are the major tasks of a combine harvester, an d what crops can it be used for?

References


DIEPENBROCK, W.; ELLMER, F.; LÉON, J., 2005: Ackerbau, Pflanzenbau und Pflanzenzüch-tung. Grundwissen Bachelor, Ulmer, Stuttgart

LAMPKIN , N, 2002: Organic Farming. Old Pond Publishing, Ipswich


SCHÖN, H., 1998: Landtechnik, Bauwesen - Verfahrenstechniken, Arbeit, Gebäude, Umwelt. 9., völlig neubearb. und erw. Aufl., BLV-Verl.-Ges., München

Further reading




E.1–1


E.1 Plant nutrients

Pratley, 2003

� Table 6.1 shows the nutrients required by each plant.

� Oxygen (O), carbon (C) and hydrogen (H) are derived from water and air.

� All other elements must be supplied through the soil.

� The distinction of macro- and micronutrients refers to the amounts required.


E.1–2

� There is a difference between absolute and relative nutrient availability.

� Absolute availability refers to the total amount of nutrients in the soil.

� However, the relative availability for a plant depends on several factors. Very im-portant is the soil-pH (acid, alkaline or near neutral pH).

� Some nutrients become chemically unavailable at extreme pH-values, even if the total amount in the soil is high.

� Particularly phosphorus (P) has a narrow optimum availablity window.

� Note: aluminium (Al) is not a nutrient but toxic for plants at low soil-pH.

Ashman & Puri, 2002


E.2–3

E.2 Fertilization

� To recycle nutrients from animal production, manure is brought on the field. This also increases humus content of the soil and has positive effects on soil structure and biological activity.

� In conventional farming nutrients are also added as synthetic “chemical” fertilizers.

� Too high rates of fertilizer are not necessarily toxic. They may also promote dis-eases, lead to physiological imbalance or growth disturbance.

Ashman & Puri, 2002


E.3–4

E.3 Nitrogen cycle

U.S. environmental protection agencyU.S. environmental protection agency

� Nitrogen (N) is often the nutrient with the highest yield effect.

� In conventional farming synthetic N-fertilizers are applied. These are not permitted in organic farming.

� The major N-source in organic farming is nitrogen fixation from the air by plants of the legume family. These plants form a symbiosis with bacteria (rhizobia) that live in so-called root nodules of the plant.

� For this reason, legumes are an essential part of each crop rotation in organic farming.

� While other crops produce approx. 1 g of dry matter from the assimilation of 600 mg CO2, legumes must assimilate 1000 mg CO2 for the same growth, due to addi-tional energy demand of the rhizobia. This is “the cost” of being N-self-sufficient.


E.4–5

E.4 Checkup, references and further reading

� What is the meaning of the term macronutrients and which plant macronu-trients do you know?

� What may be the reason if a phosphorus deficient pl ant does not react to phosphorus fertilizing?

References



Further reading

MARSCHNER, H., 2003: Mineral nutrition of higher plants. Academic press, Amsterdam

MENGEL, K; KIRKBY , E.A., 2001: Principles of plant nutrition. Dordrecht, Kluwer

F Weed Management

F.1–1

F Weed Management

F.1 Weed biology

� “Weed” is a term for plants not wanted in an agricultural field. These are usually naturally occuring plants. Some species are especially favoured by certain agricul-tural activities and become dominant. Crops from earlier years, due to lost seeds, may also become weeds (called “volunteer crop”) in another crop.

� Important negative effects of weeds are: - direct competition with the crop for water, light and nutrients - quality reduction of harvest product due to contamination - mechanical problems at harvest, especially if weeds are still green and tough

� In conventional farming, the aim is often to wipe out all weeds chemically. How-ever, weeds also have positive effects: - better total root penetration and organic matter formation in the soil - higher biodiversity in the field, promotion of beneficial organisms (= enemies of pests) due to alternative habitats

� As a result, in organic agriculture weeds are not destroyed but controlled. A certain weed population is tolerated as beneficial. Only excessive growth must be con-fined to avoid yield or quality losses.

Lampkin, 2002 (in: Roberts, 1982)

F Weed Management

F.1–2

� Like all plants weeds can be annual or perennial, herbs (dicotyledons) or grasses (monocotyledons).

� Annual weeds germinate from seeds, grow and produce new seeds. Most weeds produce between 100 and several thousands of seeds per plant. So weeds that are allowed to spread their seed may be a bigger problem in the following year.

� The life span of seeds (during which they can germinate) depends on species and may be as low as 1-4 years, but for many weeds is rather 10-40 years.

� Typically there are between 10.000 and 50.000 seeds per m2 in the soil. However, only a small percentage meets favourable conditions for germination. Many seeds are consumed by soil organisms before they ever germinate.

� Perennial weeds like thistle (Cirsium arvense) or dock weed (Rumex crispus) have a life cycle of more than one year. They commonly have the ability to store re-serves in their root, and even if the aboveground plant dies by cold, hoeing or else, it may resprout by use of its reserves.

F Weed Management

F.2–3

F.2 Weed control

� There is a difference between indirect and direct weed control: - indirect weed control is achieved by soil cultivation (see there) and promoting a good and competitive crop (e.g. by seedbed preparation, fertilizing etc.) - direct weed control is applied in the crop with the aim to reduce the number of weeds and avoid damage of the crop

� Strategy A: destroy very young weeds with a tool that is survived by the already larger crop plants. The harrow (Fig. 6.4) is used in this way. It is applied when the crop is large enough to be unharmed. Young weeds are torn out or smothered with soil. Weeds that are already larger (like the crop) will survive.

� Harrows for weed control are more gentle than those for seedbed preparation.

Lampkin, 2002Lampkin, 2002

� Strategy B: destroy all plants between the crop rows. This is generally achieved with a hoe that can also be used on a tractor. The weeds are cut closely below the soil surface and effectively destroyed. Weeds standing in the crop row will survive. Exact steering of the machine is required - else the crop will be destroyed, too.

single tool of a machine hoe

� A combination of hoe and harrow is very effective and common.

� There are lots of other tools, but the basic strategies are the same.

F Weed Management

F.3–4

F.3 Checkup, references and further reading

� What are weeds, and how can they be classified in t erms of weed manage-ment?

� What are the major negative and positive effects of weeds?

� What is the difference between direct and indirect weed control?

� What are the basic weed control strategies of hoe a nd harrow?

References


Further reading




botanical names german english

Starch Crops Avena sativa Hafer oat Hordeum vulgare Gerste barley Secale cereale Roggen rye Triticum aestivum ssp. vulgare Saat-, Weichweizen wheat Triticum aestivum ssp. spelta Dinkel spelt (wheat) Triticum durum Durum durum (wheat) Triticosecale Triticale triticale Zea mays Mais maize, corn

Oil Crops Brassica napus ssp. napus Raps oilseed rape, rapeseed Helianthus annuus Sonnenblume sunflower Linum usitatissimum Lein, Flachs Flax, linseed Cannabis sativa Hanf hemp

Protein Crops Pisum sativum Erbse pea Vicia faba Ackerbohne faba bean, field bean Glycine max Sojabohne soybean

Root and Tuber crops Beta vulgaris Zuckerrübe sugar beet Solanum tuberosum Kartoffel potato

Forage Crops, Catch Crops Brassica rapa ssp. oleifera Rübsen (bird or turnip) rape Lolium multiflorum Welsches Weidelgras Italian ryegrass Medicago sativa Luzerne alfalfa, lucerne Phacelia tanacetifolia Phazelie phacelia Sinapis alba Weißer Senf white mustard

Weeds Elymus repens Quecke quack-grass, common couch Cirsium arvense Ackerkratzdistel creeping / Canada thistle Galium aparine Klettenlaubkraut cleavers Stellaria media Vogelmiere common chickweed

Plants of Grassland Alopecurus pratensis Wiesenfuchsschwanz meadow foxtail Arrhenatherum elatius Glatthafer tall oat grass Dactylis glomerata Knaulgras orchard grass or cocksfoot Festuca pratensis Wiesenschwingel meadow fescue Lolium perenne Deutsches Weidelgras perennial or English ryegrass Phleum pratense Wiesenlieschgras timothy Poa pratensis Wiesenrispengras Kentucky bluegrass Trisetum flavescens Goldhafer golden oat grass Trifolium pratense Rotklee red clover Trifolium repens Weißklee white clover

Renewable Raw Material Populus spp. Pappel poplar Salix spp. Weide willow Miscanthus spp. Miscanthus

Chinaschilf miscanthus

Panicum virgatum Rutenhirse switch grass



cm centimter = 0,01 m

CO2 carbondioxide

DM dry matter

dt decitonne = 0,1 t = 102 kg

e.g. for example (exempli gratia)

fig. figure

ha hectare = 104 m2

kg kilogramme

l litre = 0,001 m3

m meter

m2 squaremeter

Mg Megagramme = 106 g = 1 t

mm millimeter = 10-3 m

Mpa Mega-Pascal (unit of pressure)

µm micrometer = 10-6 m

pH scale for acidity (0-7) or alkalinity (7-14)

ppm parts per million (0,0001 %)

P.T.O. power take-off

t tonne = 103 kg

Index

Index

acre.......................................................... B.4–1

assimilates............................................... A.3–6

autumn-sown........................................... D.1–1

biosphere................................................. B.1–1

bud........................................................... A.2–3

bushel ...................................................... B.4–1

C3-plants ................................................. A.3–6

C4-plants ................................................. A.3–6

capillarity.......................................B.3–5, D.4–7

carbondioxide .......................................... A.3–6

Cereals .................................................... C.1–2

clay .......................................................... B.3–3

clover ..................................................... C.6–10

cob........................................................... A.2–4

combine harvester................................... D.5–9

Cotyledons .............................................. A.1–1

crop rotation ............................................ D.2–2

crumbs..................................................... B.3–4

cultivars ................................................... A.1–1

day length................................................ A.3–8

decitonne................................................. B.4–1

Dicotyledons............................................ A.1–1

direct weed control ...................................F.2–3

ear ........................................................... A.2–4

evapotranspiration................................... A.3–5

family ....................................................... A.1–1

fertile soil ................................................. B.1–1

field capacity............................................ B.3–6

forms........................................................ A.1–1

Fruits........................................................ A.4–9

generative stage...................................... A.3–8

genus....................................................... A.1–1

grassland............................................... C.7–11

Green fodder ......................................... C.6–10

harrow...........................................D.4–7, F.2–3

hoe............................................................F.2–3

humus...................................................... B.1–1

hydrosphere ............................................ B.1–1

indirect weed control ................................F.2–3

inflorescence ........................................... A.2–3

internodes................................................ A.2–3

leaves ...................................................... A.2–3

legumes................................................... E.3–4

lithosphere............................................... B.1–1

Loam........................................................ B.3–3

loosening .................................................D.3–4

Macropores.............................................. B.3–5

maize .......................................................C.1–2

Mesopores ............................................... B.3–5

micropores ............................................... B.3–5

mineralization........................................... B.1–1

Monocotyledons....................................... A.1–1

monoculture .............................................D.2–2

mouldboard plough..................................D.3–4

Mu............................................................ B.4–1

nitrogen fixation ....................................... E.3–4

nodes ....................................................... A.2–3

non-food uses ........................................C.8–12

nutrient availability ................................... E.1–2

nutrients ................................................... E.1–1

oil seed crops...........................................C.3–6

permanent wilting point............................ B.3–6

photosynthesis......................................... A.3–6

plant-available water................................ B.3–6

pores........................................................ B.3–5

potatoe.....................................................C.4–7

proteincrops .............................................C.2–4

PTO shaft.................................................D.4–8

raceme..................................................... A.2–4

rhizobia .................................................... E.3–4

rice ...........................................................C.1–2

roller .........................................................D.4–7

root........................................................... A.2–3

root hair.................................................... A.2–3

root nodules ............................................. E.3–4

Sand ........................................................ B.3–3

seed potatoe ............................................C.4–7

seedbed ...................................................D.4–7

silt............................................................. B.3–3

Soil ........................................................... B.1–1

soil cultivation ..........................................D.3–4

soil profile................................................. B.2–2

soil structure ............................................ B.3–5

soil texture ............................................... B.3–3

soybean ...................................................C.2–5

species..................................................... A.1–1

spring-sown .............................................D.1–1

stem ......................................................... A.2–3

sugar beet................................................C.4–8

tuber......................................................... A.4–9

Index

varieties....................................................A.1–1

vegetative period .....................................D.1–1

vegetative propagation ............................A.3–8

vernalization................................. A.3–8, D.1–1

volunteer crop .......................................... F.1–1

Water use efficiency.................................A.3–5

Weed........................................................F.1–1

wheat....................................................... C.1–2

Yield .........................................................B.4–1

Documents

Organic Food Chain Management - Uni Hohenheim · PDF fileScheme of a dicotyledonous plant in vegetative state ... and transport (like sugar) or plant organic matter for ... - many