Green grams
Machakos,Makueni,Kitui,Taita Taveta,Lamu,Embu(Mbeere),Tharaka Nithi,Meru,West Pokot,Baringo.
Introduction
Green gram commonly known as Ndengu is one of the climate-resilient and smart crops grown in Arid and Semi-Arid Areas of Kenya. It is a drought-tolerant and economically nutritious food legume. It is cultivated largely by smallholder farmers under rain-fed conditions with the bulk (90%) of its production concentrated in the drier areas of eastern Kenya. It is a central income-generating agro-enterprise ranking second after the indigenous chicken.
It is a source of non-animal protein and rich in vitamins, folate, and iron, and it's vital for improving the diets of vulnerable rural communities, that mainly rely on starch-based diets. It cooks faster compared to other dryland legumes (common bean, Dolichos lablab, pigeon pea, chickpea) with less flatulence. The green peas can be boiled with green maize to make githeri. It can also be mashed with Irish potato, sweet potato, banana, arrow roots, and pumpkins to make mukimo
Green gram fits in major cropping systems - mono and inter-crop. Through symbiotic nitrogen fixation, green gram harnesses atmospheric oxygen and contributes to a positive nitrogen balance in the soil. It also adds considerable biomass to the soil, improving nutrient status, and maintaining soil structure and microbial activity.
Climate Information
● Green gram grows in a wide range of climatic conditions. A warm humid climate with a temperature range of 25 - 35°C. and 400-500 mm of rainfall well distributed during the growing season.
Climate Change Impacts
● Rainfall amount and distribution is the most important environmental factor determining production with yield greatly affected by drought stress particularly when drought coincides with flowering, early pod setting, and pod filling.
● The seasonal rainfall over the south-eastern green gram growing areas of the country is expected to increase in both the first and second rainy seasons in the future. The early onset and longer length of the growing period are anticipated in this region which favors the green gram agricultural activity in the Eastern region. However, seasonal rainfall is expected to decline in the western Greengram growing areas. This delay in the onset and a decrease in the length of the growing period is anticipated in the western green gram growing areas of the country which will have a great negative impact on the grain yield of the green gram in the region.
KAT N26
• Selection from local collections thus adapted to Kenya environments
• Dry grain color: shiny green.
• Late maturity duration (80-90 days)
• Potential yield: 1000 -1500kg/ha
• Medium seed size: 4-5g/100 seeds
• Heavy grain weight
Marketability: High
KS 20
• Dry grain color: dull green
• Maturity: 75-80 days
• Potential yield:1000-1200kgs/ha
• Large and well-filled pods
• Large grain size: 6-7g/100 seeds
• Marketability: High
Karembo
• Dry grain color: shiny green
• Maturity: 70-75 days
• Potential yield:1500-2100kgs/ha
• Large pods
• Large grain size: 8 -9g/100 seeds
• Marketability: High
Biashara
• Dry grain color: shiny green
• Maturity: 70-75 days
• Potential yield:1500-2100kgs/ha
• Large pods
• Large grain size: 8-9g/100 seeds
Ndengu tosha
Green gram is sensitive to waterlogging and high salinity. Poor tolerance to wet soils/wet conditions
Access to Farm Inputs: Approved agro-inputs dealers, research organization
Seed Sources: Approved agro-inputs dealers, research organization
Soil:
Grown on a wide range of soils including red laterite soils, black cotton soils, and sandy soils.
• Well-drained loamy to sandy loam. Not in saline or alkaline soil or waterlogged.
• PH ranging from 5.5 to 7.5.
Altitude: 0-1600m above sea level. Above 1800m, it has a very poor pod set.
Rainfall: 350-650 mm rainfall, well distributed during the growing period of 60 – 90 days. • Too much rain or long dry spells reduce yields and causes flower abortion
Temperature: A warm humid climate with temperatures ranging from 25°C to 35°C
Clear the field of any weeds and debris.
● Plough or till the land during the dry season to loosen it, remove any weeds and debris as well as expose the soil-borne pathogens to the sun. Level the land by harrowing properly to ensure uniform irrigation and germination.
Soil Management
● Use of well-decomposed manure is encouraged for balanced soil nutrients and improved soil structure.
● Intercropping and rotations aiming at optimizing the use efficiency of the applied nutrients and improving crop productivity
● Green gram is planted in both Short rain (October-December) and Long rain (March-May) cropping season.
● Choose a variety/varieties that suit the weather conditions or market demand/target market. The use of certified seeds is highly recommended as it reduces the spread of seed-borne diseases.
● The recommended spacing is 50 cm by 10 cm. Under conservation agriculture, the spacing is reduced to 45 cm by 15 cm
● Contour beds or ridge and furrow systems are useful in preventing water-logging by draining excess surface water and preventing soil erosion. With the use of a riper, planting is possible even on unploughed land where minimum tillage, popular with the Conservation Agriculture (CA) is practiced. Thereafter shallow weeding using hand hoe or herbicides to minimize tillage is recommended.
● It can be grown either as a single crop (mono-cropping) or as an intercrop (mixed cropping) with other crops.
● Intercropping promotes sustainable climate-resilient green gram cultivation as it improves the productivity and stability of yield and helps in soil conservation thus reducing the risks of crop failure.
- It is important to carry out a SOIL TESTING to determine the status of the soil in terms of nutrient availability with respect to what green gram requires. Apply well-decomposed manure or compost manure before planting. If soil is of poor fertility, 10-12 tonnes/hectare of well-decomposed farmyard manure should be applied.
- A combination of animal manure and inorganic fertilizers during planting is recommended where soils are very poor as it gives a good yield.
- Top dressing is NOT recommended since the high availability of nutrients fertility makes the crop too vegetative and thus compromises the grain yield.
A combination of animal manure and inorganic fertilizers during planting is recommended where soils are very poor as it gives a good yield.
Top dressing is NOT recommended since the high availability of nutrients fertility makes the crop too vegetative and thus compromises the grain yield.
Irrigation scheduling: Green gram requires adequate soil moisture for germination, vegetative growth, flowering, and pod development. Implement an appropriate irrigation schedule based on soil type, weather conditions, and crop stage. Avoid over-irrigation, which can lead to waterlogging and foliar and root diseases (bacterial blight, bean anthracnose), as well as under-irrigation, which can result in yield reduction. Maintain soil moisture at a suitable level, allowing the soil to dry slightly between irrigation events to avoid waterlogging
Mulching and crop residue management: Apply organic mulch, such as crop residue, straw, or dry grass, to the soil surface around the green gram plants. Mulching helps conserve soil moisture by reducing evaporation and suppressing weed growth. It also helps regulate soil temperature, prevent soil erosion, and improve soil structure.
Drip irrigation: Consider using drip irrigation systems for green gram cultivation. Drip irrigation delivers water directly to the plant roots, minimizing water wastage through evaporation or runoff. It also reduces the risk of foliar diseases and promotes efficient water use.
Heavy rainfall results in increased vegetative growth with reduced pod setting and the development of diseases like anthracnose and bacterial blight.
● Pre-Planting Weed Control: Remove the weeds and their roots from the field to prevent re-growth and to minimize weed competition with young green gram plants during their early growth stages.
● Timely Sowing: Ensure timely sowing of green gram seeds to maximize crop competitiveness against weeds. Delayed sowing can lead to weed establishment and increased competition for resources.
● Mulching: Apply organic mulch, such as straw or crop residues, around green gram plants to suppress weed growth reducing soil moisture loss, and creating physical barriers for weed emergence.
● The most common weeding method is the use of an oxen-drawn plough to remove early weeds followed by hand weeding. Second weeding should be done before flowering to avoid flower falling due to shaking the plants, which would reduce the yield. When weeding ensure earthing is done to ensure covering of the root system. This prevents overheating as well as improves anchorage and therefore prevents lodging.
● Weed control can also be maintained by using herbicides.
● IPDM is one of the climate-resilient agricultural practices that is recommended for pest management in Green gram production.
● The goal of the IDPM approach in bean production is to eliminate or reduce initial pests, reduce their effectiveness, delay the onset of a pest attack, slow down pest spread, reduce/or eliminate the use of pesticides, reduce greenhouse gas emissions, and ensure health and safe diets.
● Scouting, also called crop monitoring, is a key tool in IPDM. Its objective is to detect problems before any intervention is executed or before the problems get out of control. Crop scouting must be regular; at least once a week and should be carried out in the morning hours.
The most important pests and diseases of common beans and their management practices are discussed below.
Aphids
● Use recommended insecticides
● Alternate insecticides to avoid pest resistance
● Avoid late planting
● Improve soil fertility by enriching the soil through the use of manure and compost – increases both crop vigor and resistance to pests.
NB: pests and diseases mostly attack the weak malnourished plants
Whiteflies
Black beetle
● Spray recommended various insecticides
● Alternate insecticides to avoid pest resistance
● Avoid intercropping with other legumes as they share the same pests
Pod-sucking bugs (Clavigralla spp.) (spiny brown bug)
● Adults are difficult to control since they are very mobile.
● Immature bugs can be handpicked and destroyed
● Spray recommended various insecticides
● Alternate insecticides to avoid pest resistance
● The main natural enemies of bugs are egg parasitoids, assassin bugs, and ants which can be encouraged by conservation.
Bruchid (Storage pests)
● Post-harvest losses can be above 90%.
● Thresh and dry the grain/seed to moisture content of 12%
● Clean the seed before dusting it with storage chemicals.
● Treat with recommended storage chemicals before storage.
● Store in hermetic bags
Bacterial blight
● Use tolerant varieties
● Use of recommended copper-based fungicides
● Use certified/clean seeds
● Maintain field hygiene by removing crop residue, and uprooting diseased plants to prevent further spread
● Crop rotation
● Deep plowing to destroy plant remains.
Powderlymildew
Fungal disease
-Disseminated by wind
-Favored by cooler conditions
-Significant yield loss can occur if the disease develops before or at flowering particularly if the crop is under moisture stress conditions
Use fungicides
Use disease-free seed
Bean anthracnose
● Seed infection is a major source of anthracnose transmission to the next generation
● The disease attacks both the stem, pod, and seed
● Cultural practice by removing the debris
● Do not harvest seeds from infected plants
● Ensure adequate spacing to promote foliar drying
● Weed control to promote proper air circulation and decrease moisture in the foliar canopy
● Avoid over-irrigation since it wets and liberates fungal spore mass on foliage
● Biological control by seed dressing with Trichoderma varied
● Chemical control
Halo blight
● Rotational with non-host crops like cereals and cotton
● Deep plowing to bury and destroy the pathogen and infected debris. –Avoid weeding the field when wet.
● Removal of all infected seedlings from the field and burn.
● Suppression by spraying crops with registered copper-based fungicides
Mungbean Yellow Mosaic virus
● Viral disease spread by Whiteflies
● Scattered yellow spots on the leaves.
● Infected plants produce fewer flowers and pods: pods tend to be small
Management
● Control whiteflies
● Use tolerant varieties
● Diseased plants should be rogued out to prevent further spread of the disease.
● Crop rotation
Harvest Management and Harvesting Procedures
● Harvest when the pods are mature and dry before they shatter. Harvesting is done by plucking dry pods.
● The plucked dry pods are sun-dried for 3 to 5 days, then threshed by either beating with a stick or using a thresher.
● Immature harvesting may lead to poor grain quality and chances of infestation during storage.
● Delay in harvesting leads to shattering of pods and sprouting of grain in case of rain.
Post-harvest handling and management
● Threashing is done manually by beating the dry pods with sticks. However, with the use of a thresher, can save labour cost and time.
● The threshed grain should be dried to a Moisture Content (MC) of 10-12%. High MC lead to growth of mould thus fungal infection.
● Proper drying of grain is very important to prevent the growth of fungi and contamination with aflatoxins.
● Threshed seed is cleaned, sorted to remove all the damaged grain.
● The grain is treated and stored in bags.
Storage: The grain should be properly dried. The ideal moisture Content (MC) level is 10- 12%. High MC lead to the growth of mold thus fungal infection. Proper drying of grain is very important to prevent the growth of fungi and contamination with aflatoxins. Threshed grain is cleaned, sorted to remove all the damaged grain. Green grams are very susceptible to bruchid (storage pest) attack and are best stored immediately after sun drying either in hermetic bags. The grains can also be dusted using different formulations of storage dust at rates of 50gm per 90 kg bag.
Value Addition
Utilization: It is consumed as a pulse prepared by boiling the whole dry grain and eaten together with cereal-based meals (Ugali, chapatti, or rice). The grain can also be cooked and mashed with Irish potatoes, green bananas, sweet potatoes, and pumpkin fruit.
Yield potential
Grain yield depends on the season, rainfall, and crop management. All factors being constant the grain yield of approximately 1500 kgs/ha.
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