MAIZE PRODUCTION
consumed directly as a confection rather than a staple food. (Central Mexico). 5. Flour maize (Amylacea) – Kernels are almost entirely soft starch. (Bogotá and Peru). 6. Waxy maize (Ceratina) – Kernels have a waxy appearance. 7. Pod maize (Tunicata) – Individual kernels are enclosed in a pod or husk. This is more of an ornamental type; the gene involved produces long glumes which form part of the flowers enclosing each kernel individually. (America).
(Compiled by Shadreck Hunduza) 1.0 BOTANICAL CLASSIFICATION Family- Graminae Genus- Zea Species- Mays Botanical name-Zea mays
USES OF MAIZE
TYPES OF MAIZE 1. Dent maize (Indentata) – Dent in the crown of the kernel (Mexico) The sides of the kernel are flinty while the centre is floury. These varieties are relatively softer than the flinty types and can easily be ground by hand when dry. They are commonly grown for the daily human consumption. 2. Flint maize (Indurata) – Have a hard endosperm, Kernels are smooth with little soft starch and are almost impossible to grind by hand when dry. Advantages: Are more resistant to insect attack, has a good germination and can be stored longer. (Central America). 3. Sweet corn (Saccharata) – Contains sweet starch. It has a sugary gene which prevents or retards the normal conversion of sugar into starch during development of the endosperm and the resulting kernels are sugary wrinkled and glossy. It is grown for canning or eaten fresh as a vegetable. (America). 4. Popcorn (Everta) – Is basically a small kernelled flint type. Kernels may be either pointed (rice type) or rounded (pearl type). Hard starch surrounds soft starch causing variations in expansion during heating resulting in popping. Some varieties have very thick skins to give high popping expansion. It is
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1. Staple food /diet as Sadza. 2. Beer brewing (Delta beverages) and distilled into whisky (USA) 3. Fuel (Distilled into ethanol) USA. 4. Livestock feeding (it is rich in carbohydrates) 5. Expression of vegetable oils. 6. Extraction of starch for cooking and other domestic purposes. 1.1 CLIMATE Rainfall – 500-700mm per annum (average) Season quality (Distribution of rainfall within a season). A pentad is a period of 5 days. There are 73 pentads in a year starting with the first 5 days of January as pentade 1. The dates of pentad 56 (3 rd or 7th October are taken to be the start of the rainy season in Zimbabwe (arbitrary for statistical purposes). Pentad 24 (26-30th April) is the last pentad worth recording. The pentads are further divided into rainy and dry pentads: Rainy pentade: Is one which fulfils the following conditions: Take 3 pentads and the centre pentade is rainy if: a) Rainfall total for all 3 pentads is more than 40mm. b) Not more than one pentad is having less than 8.5mm; this level of rainfall is generally adequate for crop growth. Make use of farm rainfall records!
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Planting rains: +/- 25mm in 5 days on all soil types and earlyploughed sands may need only +/- 15mm. Temperature - refers to the amount of heat received which has a direct effect on the length of time for any given variety to reach maturity. A given variety will take longer to mature in colder higher altitude regions than in warmer lower altitude regions. The length of season is thus dictated by temperature. Maize needs a certain amount of energy in terms of sunlight radiation and heat to reach physiological maturity. Minimum temperature- 10 Degrees Celcius. Optimum temperatures -28 Degrees Celcius. The following formula is used to calculate heat units: Minimum + Maximum Temperatures – 10 degrees celcius = day heat units. 2 Multiply day heat units by the number of days a variety takes to reach physiological maturity (135). Season length: The longer the season, the higher the potential yield. Maize planted after 5 December will have a lower yield, even if all other growth requirements are adequate. Lower temperatures at the end of April and beginning of May will reduce the plant’s ability to produce carbohydrates resulting in poor individual grain mass. A trial conducted at ART farm showed that there is a 25% drop in mean yield comparing maize varieties planted on the 25th of October and 17 th December.
1.2 SOIL REQUIREMENTS
Soil PH: 5.0-5.5 Calcium chloride scale. Soil type/texture: Maize can be grown on a wide range of soils with varying success but the heavier textured sandy clay loams) that are inherently fertile are preferable. Drainage: maize is very sensitive to water logging thus poorly drained and badly aerated soils should be avoided unless practices like ridge tillage, drainage and early planting are 3 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
employed. Maize is susceptible to drought and it can cause serious losses during the four weeks from silking to tasseling. Some form of water conservation is important e.g. Pot holing, stubble mulching and tie- ridging. Depth- it does well on deep soils.
1.3 Rotations Fits well in rotation with other crops e.g. Soya beans, Cotton, Tobacco, and vegetable crops. Tobacco – Maize rotation gives the bets yields. 1.4 VARIETIES AND VARIETY CHOICE Factors in the choice of a variety: a) Yield potential b) Disease resistance c) Season length d) Soil type e) Use of crop Classification of Seed co maize varieties: Very early maturing hybrids: are denoted by a SC 4 and symbolized by a Monkey and will take an average of 130 days to reach maturity. (SC 401; 403; 405; 407 whites) These are ideal for natural region 5 (Marginal rainfall) or for later plantings in high rainfall areas. Early maturing hybrids: Are denoted by a SC 5 and symbolized by a Zebra and will take approximately 130-140 days from planting to maturity. (SC 501; 513; 517; 521 and the yellow SC 506) These are recommended for natural region 4. Medium maturing hybrids: Are denoted by a SC 6 and is symbolized by a lion. (621, 627 whites) and SC 602 &604 (yellows).These are ideal for natural region 3& 4.These will take about 140-150 days to reach maturity. Late maturing hybrids: Are denoted by an Elephant and a SC 7. (SC709, 713, 713 (whites), 704& 706 are yellows. Late maturing hybrids will take approximately 151 – 155 days from planting to maturity. These are ideal for natural region 1 & 2 (high potential areas). 4
PIONEER HYBRIDS (PHB): 30G19; 30G97; 30B50; 3253 and 30D97. 1.5 SEEDING RATES: 25kg /ha. 1.6 LAND PREPARATION Is perhaps one of the most important operations in growing maize. If not correctly done can be costly to the farmer owing to reduced crop yields. Methods of land preparation: a) Conventional tillage (ploughing and discing). The ploughing depth is about 15 inches. Early ploughing sands as for Tobacco can be practiced. The heavier soils can also be ploughed as early as possible in the median condition before they dry out excessively. See tobacco for advantages of early ploughing. The top 80mm should have a fine tilth for efficient seed germination. b) Conservation tillage: Does not invert soil and aims to leave at least 30% of trash on the soil surface. This involves the use of tines, chisels and direct seeding planters: Strip tillage, Furrow planting and Zero tillage. 1.7 PLANT SPACING, POPULATION AND ARRANGEMENT Inter row spacing: (m) 0.75 – 0.90 are the most common spacings. The choice of inter row spacing is determined by the method of weed control, purpose of crop and moisture availability. With the advent of herbicides most of the row spacings have been shifted from 1 m to 0.75m. In row spacing (m) 0.20 – 0.60.This depends largely on plant population desired, environmental yield potential, hybrid lodging score and plant arrangement. See Seed co hand book.
1) Climatic conditions-Marginal areas use low population 2) Variety-Late maturing use low population 3) Available water: Marginal areas – low population 4) Yield potential: Higher potential crops Irrigated and waterplanted- higher population. 5) Soil productivity: High clay content higher fertility & thus high population. Marginal areas (dry land, low rainfall): Minimum of 37 000 plants per hectare. High potential areas/ irrigated, high rainfall, fertile soils good, management): 65000 plants/ha. Optimum: 55 000 plants/ha Remember a 10 – 15 % allowance should be given over and above the intended target harvest population to cover the loss of plants that fail to emerge. In hand planting one may plant an extra pip and then thin out after emergence. Effects of increasing plant population beyond the optimum: Increases: a) Plant height. b) Cob height c) Lodging d) Water and nutrient stress Decreases: i) Stalk thickness ii) Cob size iii) Seed size This is demonstrated by the maize stress wheel. SEED MAIZE SPACING GUIDE LINES Inter row (m) In row (m) 0.9 0.9
TARGET HARVEST (FINAL) PLANT POPULATION Factors affecting plant population: 5 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
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0.18 0.36
No’ of pips Plant /station population /ha 1 61 728 2 61 728
0.9
0.35
2
63 492
/ha)
ROW CONFIGURATION 3 rows female: 1 row males. Males only provide pollen can be destroyed or consumed as green maize or harvested as grain. 1.8 FERTILIZATION Factors to consider when deciding fertilizer rates: i) Correct and reliable Soil analysis. ii) Land history. iii) Soil fertility iv) Climate v) Yield target Good maize yields need good fertilization, selection of the right fertilizer, correct fertilizer rate and timing of application. The following table gives a general fertilizer recommendation (very approximate guide because no 2 soils are the same):
Yield potential of maize Less than 3 - 5t /ha 5 - 8t /ha 3t/ha Compound D 0-150 kg 100-250 250-350 e.g.8:14:7 /ha kg /ha kg /ha NPK (0(2-5 bags (5-7 bags 3bags/ha) /ha) /ha) Fertilizer type
Ammonium nitrate 34.5% N
50-150 kg (13bags/ha)
8 - 12t /ha 300600kg /ha (6-12 bags /ha)
100-250 250-350 250-500 kg kg kg (2-5 bags (5-7 bags (6-10 7
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/ha)
bags /ha)
Timing of application Compound fertilizer: The compound fertilizer must be applied at or before planting. The best method of application is by hand dolloping in the planting hole using the predetermined cup size. When using planters they should be set to apply the fertilizer in a band 5cm deep and to the side of the seed. Top dressing: Apply the top dressing fertilizer 4-6 weeks after planting. The top dressing fertilizer should be split into 2 applications especially in sandy soils, (1 st application – 4 w.a.p. and second – 6 w.a.p.). One may choose to apply the first top dressing 6 w.a.p. and the second top dressing at flowering (silking and tasseling). All the nitrogen fertilizer required can be applied in a one-off operation in clay soils because they are less prone to leaching. Methods of application Can be banded 4 inches along the row using a Chola fitted with a pipe. On large scale it can also be broadcasted over the top using fertilizer spreaders but this will temporarily scorch the leaves. 1.9 PLANTING Planting dates: The earlier the maize is planted, the higher the yield 1 st September – irrigated maize for green Mealies in most areas. October-November plantings: dry land maize highest yields but may need irrigation or planting in the vleis, very ideal for high veld conditions. November plantings with the onset of rains: safest for dry land conditions. December plantings especially in the high veld: Very risky and not recommended because of the following factors: Crop may suffer from drought stress at the end of the rainy season, it produces low yields, while weeds pests (stalk borer) and 8
diseases (Streak virus, grey leaf spot) are more prevalent on late- planted crops.
Sands: are the best because they reach field capacity early i.e. with less water.
Advantages of early planting: i) Increases the length of season and therefore increase grain fill. ii) Pollination period is advanced (occurs earlier) and may be complete before the mid-season drought which occurs in most areas. iii) October and November provide the greatest number of heat units, hence early planting will greater accumulation of dry matter provided moisture is not limiting. This is particularly important in the high veld where temperatures fall quickly with the onset of rains. iv) Plants develop a more vigorous root system if planted before the main rains start. v) Weed control is easier.
2. Dry planting: A system in which dry seed is planted in completely dry soil. Dry planting is usually done 2 – 3 weeks before the onset of the main planting rains. The following planting depths should be adhered to: Sands: 25-30 mm Heavy soils: 50-75mm. These depths are deep enough to avoid penetration of moisture from light showers and shallow enough to receive early effective rains. Dry planting is risky because success depends on whether rain is adequate to allow germination and emergence or only sufficient to start the germination process but not enough and cause the seed to rot. Holing out should be done on or before the planting date. 3. Rain planting (Moisture planting): This refers to planting after the first rains when soil is sufficiently moist (field capacity). The amount of moisture that brings a soil to field capacity differs with the type of soil: Sands: 25mm, clays 35-50mm. Planting holes should ideally be done before the rains start. Do not plant into moist soil which is drying out!
Methods of manipulating season length: 1. Early planting using the following: early ploughing to conserve moisture, full irrigation and / or supplementary irrigation. PLANTING SYSTEMS IN MAIZE Types of planting: 1. Water planting: Is a system where in soaked seed (12-18 hours) is planted in a hole in which water has been applied. The hole is then covered with dry soil which acts as a mulch to conserve soil moisture. The amount of water to apply per hole depends on the depth of residual moisture from early ploughing or pre-irrigation as for tobacco. The equipment for water planting tobacco can be used for maize planting. Seeds for machine planting should not be soaked. The objective of water planting is solely the early establishment of maize before the main summer rains commence which results in higher yields. Soils for water planting: 9 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
PLANTING METHODS Hand planting Advantages: a) Can produce very even stands if supervised properly (plant 2 pips / hole thin out to 1). A high planting output is possible where holing out and fertilizer dolloping has been done ahead of the planting gang. b) Planting is not held up (hindered) by adverse weather condititions. Mechanical planting: 10
Advantages: a) Very high outputs are possible a 4ow planter can plant up to 15 hectares per day. b) Less labour is required NB-Know your machine!. 2.0 WEED CONTROL Options available for weed control in Maize: 1) Mechanical This refers to the use of tractor-drawn implements. These are however restricted to the early stages of growth. This involves use of spike toothed harrows; gang tillers; Inter row cultivators; spring tine cultivators; heavy shank spring tines; and steerage hoes. Timing of operations is very important this method is very effective during the seedling stages of weed growth. 2) Chemical weed control Herbicides registered for use in Maize: Alachlor; Atrazine; Metolarchlor (Dual); Gramoxone (Paraquat); Glphosate and EPTC. These can either be applied pre-emergent or post-emergent. 3) Hand – Use of hoes. 4) Integrated weed control system.
2.1 PEST AND DISEASE CONTROL 1) Maize stalk borer (Busseola fusca): It is the most important pest of maize. Effects: a) Young plants are permanently stunted. b) No cobs are formed. c) Weakening plus lodging of stem as a result of the tunneling activities of larvae (caterpillars). d) Cobs are ruined directly by larvae feeding on grain (kernels) or indirectly as secondary infection by fungi and the associated discolouration especially on green mealies. 11 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
Signs On young plants 0.3-1.0m high “Window pane” effects on leaves emerging from the funnel, frass (droppings) from the stem and cob. Older plants- dirty white caterpillars are found tunneling in stems, frass protruding from holes, dry tussels or tussels breaking off. Alternative hosts Sorghum, cotton, Millets, sugarcane and Tomato. Life cycle Adult: Is a moth that emerges at the beginning of the rainy and lay up to 3 generations of eggs per season. It lays eggs between base of leaf sheath and stem of host plant On hatching larvae climb up into funnel and feed for 7-9 days. They then bore into the growing point of the stem. Some will migrate from primarily infested plant to neighbouring plants. Adult larvae can enter stem at any convenient place. They undergo development for 30-45 days in the stem. Pupae:Over winter in the stem. Control: A pinch of granular contact insecticides is placed in the funnel at 4 w.a.germination or when 10% of plants show “window panning” a second application can be done 10 days later if the infestation is severe. Chemical rate Thiodan 1% granular (endosulfan) 3-4 kg /ha Dipterex 2.5%G (trichlorfon) 3-4kg /ha Carbaryl 85wp (fcs) repeat 625g /ha Dursban 4E (fcs) 350ml/ha Monochrotophos 40wsc 1l/ha 100l mix/ha 12
Thionex 35EC 300l /ha At planting Carbfuran (curatter 10%G) 200g/100m in furrow 20kg /ha Temik (seed maize only) 240g/100m 20kg /ha
d) Rogue out all infected plants in the vicinity Apply granular insecticides at planting e.g. Oncol 10%G or Currater 10%G. a) Spray crop plus a 50m swath/headland around crop with Dimethoate 40EC repeat after 14 days. 2. GRAY LEAF SPOT Cercospora leafspot (GLS) Cause: fungus cercospora zeae-maydis Importance: A sporadic disease following very wet weather conditions but Zimbabwe is generally dry for disease development. This disease has the potential to cause massive field losses. Alternative hosts: Sorghum spp and grass spp. Signs Initial pin point, opaque spots, with yellow- halos on lower leaves. These later on spread to mid and upper leaves. Spots rapidly elongate forming narrow rectangular inter veinal lesions of 5 – 60mm diameter. Lesions are initially tan; turn pale brown buff or grey in colour. Under very wet conditions, lesions coalesce, blight and desiccate whole leaves. With a severe form of the disease, lesions form on leaf stalks, stem infections causes breakage and lodging of stem premature senescence and finally death of plant. There is also reduced cob size and grain yield. Transmission 1. Fungus can survive for 1 year on maize debris. 2. Wind blown spores (airborne). Predisposing conditions: Very moist weather (13 hours of free moisture) on plants. It also spreads when temperatures are moderate (20-28Degrees Celcias) with humid and overcast rainy or misty weather. The disease is common where stubble mulching and monoculture are practiced. Control: a). Spray Gaucho as follows:
Cultural control Deep plough or burning of Stover to destroy over wintering larvae. 2.False wire worms and cutworms-chlorpyrifos as for tobacco. 3. Army worm –Carbaryl 85% wp. 4. Leaf hoppers vector of streak virus disease-dimethoate. Storage pests Maize weevils larger and small grain moths-Fumigate methyl bromide, Phostoxin tablets or super dust. DISEASE CONTROL 1. Maize streak Causal agent: Maize streak virus (MSV) same as MMV, but mmv causes stunting +cob rot. Signs Alternating dark and light green variegated stripes along leaf blades and parallel to leaf veins. Early infected seedlings are severely stunted. Cobs become sterile or partially filled. Later infections cause less severe effects on yield. Transmission: Vector leaf hopper (Cicadulina mbila) sucking sap from infected plants. The signs spread from infected leaf to all parts above infection site. Control: a) Use of resistant varieties. b) Spray with systemic aphicides to kill the vector leaf hopper beginning 6w.a.p. c) Avoid very early and very late plantings. 13 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
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From 60days after planting-1st spray, second spray-90 days after planting. b. Plant GLS tolerant hybrids. c. Burn or plough in infected maize debris to reduce the volume of infected mulch. One may use infected stalks as silage. d. Rotate with non-susceptible hosts. e. Avoid minimum tillage for several years. 3. BOIL SMUT (COB ANDTUSSEL SMUT) Cause- fungus Ustilago maydis, Ustilago zeae Signs Tissue of all aerial parts replaced by conspicuous greenish white to light grey or silvery galls. Galls are initially fleshy and harden later; they darken internally to olive- brown to black spores. The galls later burst to reveal a mass of black powdery spores. Transmission Wind blown and water-splashed spores it’s fortuitous enough that they are not systemic. Predisposing conditions High nitrogen fertilization or manuring. Wounds from mechanical injury due to hail or detasseling. Control a) Resistant varieties. b) Avoid mechanical injury. c) Seed dressing with Captan 50%wp. d) With few plants, remove galls before they rapture. e) Where disease is severe, burn or deep plough Stover. f) Rotate with non-susceptible hosts. g) Avoid over fertilization with Nitrogen. 4. HEAD SMUT (COB+TUSSEL SMUT) Signs Proliferation of shoot-like growths on tussel or ear, florets are later replaced by a mass of black spores, no silk develops 15 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
on ears. Plants with infected tussels will always have their ears infected. Control The control measures are similar to boil smut. OTHER DISEASES Include cob rots e.g. Diplodia ear rot, Gibberella ear rot and Fusarium (pink rot). 2.2 IRRIGATION Refer to irrigation notes. 2.3 HARVESTING AND YIELD Methods of harvesting 1. Hand harvesting- different methods are used. a) Bang board method Reaped cobs may be thrown directly into a trailer fitted with a bang board. A bang board is a wooden plank fitted horizontally on edge along the length of a trailer. Maize cobs are then thrown from either side aimed at it so that they hit it and fall into the trailer. b) Maize may be harvested and loaded into drum or sacks that are offloaded into a trailer without a bang board. Advantages a) Produces a clean crop. b) Limits cob damage and is thus suitable for seed maize harvesting. c) Human beings can glean cobs lying on the ground. Disadvantages *It is slow and thus suited to small scale operations. *It is labour intensive Factors affecting reaping output Moisture content-not a problem if reaped between 11-15%. Spacing: closer spacing-higher output. Cob size: Bigger cobs result in higher output Cob height: Too high above waist level gives low output. Lodging: It takes more time to pick cobs lying on the ground than erect cobs thus slow output 16
2) Mechanical harvesting Advantages: a) Fast and efficient b) Will chop and spread Stover ready for mulching the following crop. c) Fits in well in bulk- handling situations Disadvantages: *Steep slopes, small lands and contours will affect field efficiency of machine. *Dense weed infestations may cause blockages. *Machines will not pick up cobs on the ground and are inefficient in badly lodged crops. *Machines will not sort out badly diseased cobs. Shelling: Is easy when the crop is dry. Yield Maximum of 12 tones per hectare Marketing: Maize may be sold to the GMB (Grain marketing board) at between 11-12.5% moisture content. One may sell to private buyers such as stock feed manufacturing companies e.g. Agri foods and National foods. THE END Prepared by Hunduza S. 0913 802131
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SOYABEAN PRODUCTION (Compiled by Shadreck Hunduza) Introduction Soya beans are one of the world’s most important sources of oil and protein. In Zimbabwe Soya beans are currently second to Cotton seed in terms of amounts purchased by oil extractors. Soya beans also provide a protein rich cake used locally in Pig and Poultry feed. The protein content exceeds 40%. Zimbabwe produces 80 000 tonnes but the annual requirements are 130 000 tonnes hence we have a shortfall. The oil expressing capacity is 160 000 tonnes Per annum. The crop was of minor importance until the mid 70’s; production was and is still mainly aimed at supplying the Pig industry with high quality protein thereby minimizing the importation of Fish meal. The price of Soya beans is attractive about twice that of Maize. Soyas’ contribute to Zimbabwe’s vegetable oil requirements but we are not yet self sufficient. 1.0 Botanical classification Family – Leguminaceae, with beans, peas, cow peas and ground nuts. Genus- Glycine Species- max 1.1 Botanical name-Glycine max The Soya bean plant is a herbaceous summer annual legume with upright spreading branches. The flowers are self-pollinated and are generally white or purple. They are born in clusters on branches. Pods-Are covered in fine grey or brown hairs. They bear 2-4 seeds per pod. 18
Seeds-Are generally yellow in colour but varies from green, brown to black depending upon the variety. A crude protein content of the seed is 40% and an oil content of 20% is ideal. USES OF SOYABEANS: a) Seed b) Hay c) Green manure d) Silage e) Vegetable Soya f) Vegetable oil g) Soya milk, meat, minces. 1.1Climatic requirements Rainfall- Soya beans thrive in areas where rainfall is good or where irrigation is available. Late rains during the growing season or high temperatures as in the low veld can drastically reduce seed viability. Soya bean varieties are very photoperiodic (sensitive to day length) that is they are affected by varying lengths of day light and as a result the maturation period is affected. Only grow varieties recommended for your area. 1.2 SOILS Soya beans can be grown on a wide range of soils provided the soils meet the following criteria: *Deep *Rich in organic matter
*Well drained *Well supplied with lime. *Do not cap (T-factor) Soya beans will thrive in the following soils: Sandy loams, clay loams and heavy clays that are well drained and do not cap. If capping soils are used; care should be exercised to ensure a loose, soft friable surface at the time of emergence. Soya beans are weak germinators that means are not good “pushers”. Poor stands will therefore result if the plants 19 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
have any difficulties at emergence. Soya beans prefer heavy soils due to their high inherent fertility status and lesser risk from nematodes. Soya beans will not grow in soils where Atrazine and related herbicides have been applied to the preceding Maize crop. Soya beans, being a legume is very sensitive to soil acidity thus needs a lot of calcium supplied through lime. The ideal soil PH range for Soyas’ is 5.5-6.5 calcium chloride scale. Soyas’ will not grow in soils with a ph below 4.5 Calcium chloride scale. Lime should only be applied after soil sampling and analysis. Lime may be applied at any time in the rotation. 1.3 Crop rotations Soya beans fit in well in rotation with most crops. It leaves the soil friable and easy to plough, it is thus an excellent crop to grow in rotation with crops like Maize; Cotton; Sorghum and winter Wheat Typical Soya bean rotations * Soya-Maize-Soya * Soya-Wheat-Soya * Soya-Sorghum-Soya *Soya-Cotton-Soya Soya beans have got a high degree of susceptibility to the common root Knot nematode (Meloidogyne javanica) and as a result should not be grown in rotation with the following crops: Tobacco; Potatoes; Peppers; Tomatoes; Sun flowers and Beans. Benefits of rotating crops with Soya beans in Zimbabwe: i) Being a legume, Soya beans can fix inorganic Nitrogen (N2) from soil air that can be used by other plants in the rotation thus improves soil fertility. ii) It is an efficient user of residual fertility thus brings about nutrient recycling. iii) It discourages pest and disease build up. iv) Soya beans is a short season crop thus fits in well in rotation with other crops. v) Its residue or Stover is easy to destroy and that results in good land preparation for follow-on crops in the rotation. 20
1.4 Varieties and variety choice Soya bean cultivar groups: There are 2 groups of Soya bean varieties available for growing in Zimbabwe: a) Determinate varieties: These grow vegetatively for about 6 weeks then they begin flowering (having put on 10-12 leaves). Once flowering begins no further leaves are produced on the main stem. These are therefore cultivars that show a distinct vegetative and reproductive phase. These are better suited to the warm (fast growing areas) Low veld where irrigation is available. b) Indeterminate varieties: These grow vegetatively for 6 weeks, begin flowering when the stem has 10 leaves but the stem continues to grow during flowering. Thus in these cultivars, the vegetative and reproductive growth phases overlap. Factors to consider when choosing a Soya bean variety: *High yield potential *Good disease resistance (leaf rust, frog eye leaf spot) *High pod clearance from the ground *High resistance to lodging *Non shattering (take a long time from maturity to pod shattering). *Use: whether grown for hay (fodder yield) or for seed yield. The following is a list of seed- co Soya bean varieties: Score; solitaire; soprano; safari; siesta; santa and Sc Edmame. Sc Edmame is the new vegetable Soya bean variety with the following characteristics: >>Large seeds >>High sucrose & carbohydrate content thus is sweeter than the conventional seed varieties. >>No anti- nutritional factors which result in gas accumulation in the stomach. Flatulent causes gas accumulation in conventional Soya beans. 21 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
>>No Trypsin inhibitor which affects the enzyme that digests protein in monogastrics. >>This variety will take 65-70 days to green pod harvest and 95 days to seed harvest. >>The yield is 5t/ha as vegetable Soya bean and 2.2t/ha as seed. Advantages: *There is no need for roasting to feed monogastrics. *It reduces progression of prostate cancer, coronary heart disease and HIV in Man. Disadvantage: It shatters profusely as seed. 1.5 Seed: As Soya beans are self pollinating, the mature bean can be used for seed purposes. Extreme care should be taken when home grown seed is to ensure high germination. High temperatures and excessive rain at the end of the season can reduce seed viability therefore all seed should be germination – tested before planting. The use of certified or good quality standard seed should always be practiced. Seeding rate- Approximately100 kg /ha. Seed rate varies with seed size/count, germination % and plant population desired. 1.6 Land preparation Different tillage systems can be employed in Soya bean production depending on availability of equipment and scale of operation. 1) Conventional tillage Objectives: To produce a fairly deep; fine; firm; and level seedbed as required by Soya beans. Advantages of conventional tillage: a) Ensures better seed-soil particle contact ideal for maximum moisture transmission and absorption. b) Facilitates an even planting depth and uniform plant stand. C) A fine tilth facilitates seedling emergence. d) A fine and firm seedbed is advantageous in dry years. 2) Conservation tillage (Reduced & Zero tillage) These systems aim to leave at least 30% of the preceding crops’ residue on the soil surface; the soil is not inverted and may not 22
be tilled at all. The seed is drilled using a specialized planter e.g. Garspardo or monosem.Under reduced tillage the land can be ripped, disc harrowed before planting or may be disced and planted. With zero tillage a specialized planter is used to plant through the undisturbed stubble mulch of the previous crop. Advantages *It is cheap i.e. saves fuel machinery wear and tear. *The stubble mulch from, preceding crop conserves soil moisture; soil microbes and structure and increase yields in dry seasons. It is worth noting that Soya bean lands should be as level as possible and stone free to reduce combine losses Disadvantages: <<Weeds-the use of pre-emergence and lay bye herbicides is imperative. << May cause yield reduction in wet seasons due to water logging. 1.7 PLANTNG Inoculation and seed dressing Inoculation is the deliberate infection of seed with a known strain of bacteria (Rhizobium). Legumes are symbiotic with certain soil inhabiting bacteria which fix atmospheric nitrogen for the growth of the plant. The plant supplies carbohydrates, moisture and the bacteria supplies Nitrogen to the plant Bacteria rhizobium infect roots of legumes to form nodules in which Nitrogen fixation occurs. Nodules are distinguished from root knots (galls) in that they are always attached to the side of the root, while root knots (galls) are swellings of the root itself. It is advisable to inoculate all seed before planting because bacteria rhizobium does not normally occur in Zimbabwean soils. Nodulation test At flowering (4-6w.a.p.)-dig up a plant and check the following: Effective nodules- are always red or pink inside, large and few. Only a few large nodules can be effective. Non-effective nodules-Are white inside, small, are numerous and scattered all over the root system. 23 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
In sandy soils rhizobium can live for 2 years while in clays it may live for 4 years, it is however advisable to inoculate every year to get higher yields. Very wet soils delay nodulation by about 6-8 weeks resulting in chlorosis (Nitrogen deficiency sign appearance). Rules for inoculants use: Bacteria are living things! Storage: Store in a cool, dark place. *Inoculate immediately before planting otherwise if done too early they die of starvation and thirst. *When about to plant mix seed with a sugar solution or skimmed milk solution only sufficient enough to wet the seed to prevent damage of the seed coat. *Allow seed to dry in the shed away form ultra violet light, the worst enemy of bacteria. *Keep sacks of inoculated seed under a shady tree during planting *Sow in moist soil *Do not mix raw seed with fertilizer unless pelleted *Harrow- in broadcasted seed immediately Inoculantsâ&#x20AC;&#x2122; rate: 1packet / 100kg seed. Use higher rates in sands or first year lands. Seed co is the source of inoculants. Planting dates Like maize and other crops, the longer the growing period, the higher the yield. Rainfall during the last 6 weeks of the plantâ&#x20AC;&#x2122;s life determines yield timing of planting should be related to this aspect. It is important to time the date of planting so that the crop is ready for harvesting about mid March to early April when the rains tail off. It can be said that the earlier plantings will out yield later plantings but may run into harvesting problems. The following planting dates are suggested: High veld: 15-30 November. Middle veld: 30 November Low veld: 30 November-7 December 24
Seed dressing: Seed dressings help ensure good emergence. A fungicidal seed dressing should be applied immediately before planting i.e. at the time of inoculation but avoid Mercuric seed dressings if inoculants are used otherwise the rhizobium will be killed. The following non-Mercurial fungicides may be used: Thirum 85wp @ 85g/50kg seed, Quintozene 75wp @ 7kg/ha spot spray or Captan 50wp 125g/50kg seed. Plant spacing Factors affecting row spacing: *Tractor access for cultivation and spraying *Time taken to alter tractor wheel spacing. Inter row spacing: Top yields are obtained when rows are set at 0.45m but the crop is difficult to manage. The best row spacing is 0.6-0.75m. Twin row planting: Plant twin rows 0.2m apart with 0.9m distance between any 2 pairs of twin rows. Skip row system A wider row is deliberately left between planter rows to create easy access for spraying e.g. if a planter is a 6 or 8 rows, then a wider spacing is left between pairs of 6 or 8 rows. Wider spacings: Reduce yields of late planted crops, produce plants with a low pod clearance. Wider rows increase productivity per laborer if the crop is to be cut by sickles. Narrow rows: Encourage taller growth and high pod clearance and low harvesting losses if the crop is to be combine-harvested. Furthermore a crop canopy develops earlier, thus reducing weed competition. In row spacing: 25-50 mm apart depending on inter- row spacing chosen.
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Example: Row spacing In-row mm spacing mm 450 50 450 60 600 40 750 30 900 25
Plants /900mm Plant row population / ha 18 444 000 23 444 000 23 417 000 30 444 000 36 444 000
Plant population Top yields are achieved when the plant population is between 400 000 - 450 000 plants per hectare. Planting depth: 2.5-5.0 cm. Factors affecting planting depth: *Soil texture: deeper in sands shallower in clay. *Moisture depth: plant deeper in drier soils and shallower in moist soils. 1.8 FERTILIZATION The best guide on fertilizer use is obtained from a reliable soil analysis and land history. The following are general fertilizer recommendations: Compound D or L: 200-300 kg/ha in addition to Gypsum or Single super phosphate should be applied before planting. It should be noted that Soya beans do not need more than 30-40kg Nitrogen per hectare in the basal fertilizer. High levels of Nitrogen in starter compounds reduce nodulation despite inoculation. Soya beans respond well to manure application. The compound fertilizer should be applied before planting in a band 5cm to the side and 5cm below the seed. Top dressing Soya beans do not normally require Nitrogen top dressing under normal soils and rotations since they are able to fix Nitrogen from soil air. It should be noted that excess Nitrogen top 26
dressings will reduce yield. Where it is imperative to top dress 100-150kg/ha of ammonium nitrate may be applied. Circumstances in which extra Nitrogen top dressing is required: *Late planted Soya beans *Leached sandy soils. *If the soil around the roots become dry for any period of time. *Where there is a large amount of crop residue. 1.9 WEED CONTROL Good weed control in Soya beans is most important if high yields are to be achieved. Soya beans, being a short season crop are usually grown after the main rains have started thus it is recommended to destroy weeds by discing and then plant into a weed free land. Soya beans are a very weak competitor of weeds during the early stage of growth when they grow slowly; once a canopy is developed they smother most weeds. Options available for weed control in Soya beans: i) Mechanical- Before planting a disc harrow can be used to completely destroy early weeds in order to plant in weed free lands. After germination the crop can be effectively cultivated by a gang tiller (Millipede) until the crop is 150mm in height. If the crop is planted with maize spacing, some shallow mechanical cultivation can still be done later when the crop has grown. ii) Chemical (herbicides) The choice of herbicide depends on the weed spectrum, soil type and feasibility of application and incorporation of the herbicide. The following herbicides are registered for use in Soya beans: a) Lasso (Alachlor)-4l/ha heavy soil. b) Sencor (Metribuzine) c) Lasso + Atrazine d) Classic-30g /ha. e) Command; Dual; Foccus ultra; fusillade super and Trif. f) Linuron or Terbutryne can be used as â&#x20AC;&#x153;Lay-byâ&#x20AC;? to prevent reinfestation from late weeds. A desiccant herbicide (Paraquat) can be used just prior to harvest to kill off all green tops before 27 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
combining. Thick stemmed late weeds e.g. pig weed and apple of Peru may not dry out in time thus have to be hand-pulled before combining. 2.0 IRRIGATION Three stages critically require irrigation a) Germination and emergence day 1-6 after planting. b) Flowering days: 55-75 after planting. c) Pod fill days: 95-125 after planting. 2.1 PEST AND DISEASE CONTROL Soya beans are attacked by about 5 insect pests which include Semi-loopers caterpillars, Cut worms, American boll worms, Aphids and Snout beetles. The last 4 pests are occasional, but Semi-loopers can be expected in most years. Two or even three attacks may occur in a season, the first usually late in December or early January. 1. Semi-loopers: Are by far the most serious pest of Soya beans .The young larval stages scarify the leaves and this damage may go unnoticed till the skeletonizing of leaf tissue by the older stages of loopers is obvious. Control Scout for young larvae during crop growth especially during the flowering and seed-filling period and spray the following: a) Monocrotophos 40 %EC. b) Trichlorfon c) Endosulphan 35% EC. d) Spray with Plusia Nuclear Polyhedrosis Virus (PNPV) This is a natural occurring viral disease which kills and causes the caterpillars to turn black; the dried bodies of the caterpillars hang by their rear legs from the plant. One can crush and spay the dead caterpillars to spread the virus to control living caterpillars. 2. CutwormsDamage: Cut stems at ground level Timing: Early vegetative stages. Control: Keep lands weed free, spray the following: 28
Fastac, Karate, Decis, Dipterex bait, Fenvalarate or Thiodan bait. 3. American boll worm (Helliothis armigera): Spray Carbaryl, Nuvacron or Thiodan. 4. Root Knot Nematodes: “Soyas” are good hosts to root knot nematodes (Meloidogyne javanica)- Rotate with non-hosts. Do not rotate with Tobacco or sunflower. 5) Aphids and Red spider mites: May be controlled by spraying Dimethoate or Thiodan. Summary Chemical formulations: WP: Wettable powder MO: Miscible oil EC: Emulcifiable concentrate WSC: Water soluble concentrate Application methods Fcs: cover spray
Pest Semi lopper
chemical Carbaryl
formulation wp
Thiodan or Thionex Heliothis
Carbaryl Monocrotophos
Mo EC wp wsc
cutworm
Fenvalerate
EC
Aphids +RSM
Dimethoate
EC
800-1000ml/ ha
Soya bean Diseases 1. Soya bean rust (Phakopsora pachyrhizi) The disease was first recorded in 1997/98 when it caused severe losses. All varieties available at present are susceptible. Signs Numerous small grey to russet-coloured tufts on the underside of leaves (appear similar to red spider mite).Later on leaves appear yellow-brown. When plants are shaken, a light-brown cloud of spores like dust may be seen in and above the canopy. Control a) Use the following fungicides: Punch Extra at 350-500ml/ha. b) Shavit at 500ml /ha. Timing *Late vegetative-early flowering: Scout for rust * First flower (50d.a.p)-Apply first prophylactic spray * 70 d.a.p.-2 nd spray *90 d.a.p.-3rd spray Others a) Frog eye leaf spot (fels) Small dark brown spots which may turn buff or grey. Spots may Rate/ha Application details coalesce and cause premature leaf drop (abscission). 1kg Mix with Control 5 % molasses by vol, Rotate with non-hosts. Plough in all crop residues. repeat as necessary Use certified seed. 300 – As above b) Red leaf blotch: 1000ml Cause: Fungus Pyrenochaeta Glycine Small angular dark purple-red spots along the main veins of 1kg As for semi looper lower canopy leaves. Moist humid weather accelerates lesion 300-600 ml Mix with 100l H2o, apply 200l/haenlargement. Spots then change colour to pinkish-red and are boarded 800ml /ha 300mm band overby chlorotic haloes. In severe cases disease cause acute 29
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defoliation prior to flowering and death of plants or reduced yield. Control: Destroy crop residues, resistant varieties e.g. Solitaire, *Use fungicides e.g. Brestan (fentin acetate), @ 1kg /ha spray at onset of disease and repeat at 14 day intervals after flowering. * Score 250 EC: At 300ml /ha: 2-3sprays @ 600l spray mix /ha. Repeat @ 14 day intervals after flowering. 2.2 HARVESTING AND YIELD The average yield is 3.0t/ha. Harvesting is one of the most critical operations in profitable soya bean production. When to harvest? It is important to be able to recognize the 2 stages of soya bean maturity: a) Physiological maturity When the bean will no longer increase in dry matter and the plant has ceased to translocation water and nutrients. One brown pod on plant, most leaves are yellow and fallen off the plant, seeds rattle in the pods. Do not delay harvesting after leaf fall, since the drier the pods become the greater the degree of shattering and loss of yield. The seed has a moisture content of 30-35 % too wet to harvest but hand cutting and wind rowing should commence. b) Harvesting maturity Occurs 1-2 weeks after physiological maturity, most pods are brown and a handful of pods will shatter easily when squeezed. Most leaves have fallen; the seed has about 20% moisture content. Harvesting methods Is determined by the following factors: *Area planted; weather;moisture content of seed;availability of combines, labour and stationery sheller;availability of drying facilities;presence or absence of weeds and use of crop. a) Hand harvesting 31 Create PDF files without this message by purchasing novaPDF printer (http://www.novapdf.com)
Ideal for small areas if plenty of labour is available, sickles may be used to cut the plants early in the morning before pods begin to shatter. The stems can also be hand pulled if the crop is well dried. A variation of this method is to use a reciprocating mower to cut the plants and then use a mechanical winnower to clean the seed. Advantages: i) Minimum losses are encountered. ii) High quality Soyas are produced iii) Harvesting can commence earlier before pods begin to shatter iv) High germination viability thus is suitable for seed Soya production. b) Combine harvesting Advantage Large areas can be cut within a short period of time. Disadvantage High field losses are inevitable. The hiring costs are high. Reducing combine losses: * Land plane if necessary uneven lands greatly reduce combine efficiency, increase cutter bar losses and seed soiling. * Ensure high- podding by using correct population for thick even stands. * Keep lands weed- free, hand â&#x20AC;&#x201C;pull late weeds before combining Measuring Soya bean harvesting losses This is based on 50 beans per square metre, equivalent to about 100kg /ha. A square metal frame of 8-10mm round iron should be made up or 30mm * 4mm flat iron, each side measuring 316mm. This gives an enclosed area of 0.1 m2.The beans within the frame are counted, if more than 5 or 6 beans are found on average then its equivalent to 100kg /ha loss. Drying 32
To minimize soya bean losses and reduce probability of damage from weather hazards, harvest as soon as beans reach maturity. Harvest at 18 â&#x20AC;&#x201C; 20% moisture if drying facilities are available. Dry to 11% moisture. Drying can be achieved by use of bulk tobacco bulk curers or naturally in the field if the weather is favourable. If the weather permits, it is more economical to leave the beans to dry naturally to 15 â&#x20AC;&#x201C; 16%. Forage harvesting Hay or silage can be made from Soya bean plants cut when seeds are half developed in the first formed pods. 2.3 Marketing Soya beans market has been liberalized: a) Sold to the Grain Marketing board at 11% moisture content b) Stock feed processing companies c) Oil expressing companies d) Farmer to Farmer. Prepared by S. Hunduza (0913 186175). 0913802131. THE END
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