Maize Land preparation

A maize farm can be prepared using either conventional or Conservation Agriculture (CA) methods. Conservation Agriculture, includes spraying with recommended herbicides and crop residue management. Conventional methods include hand cultivation, use of an ox-plough or a tractor (figure 1). It is important to prepare the land early enough to allow weeds to dry and decompose before planting.
Fig. 1: Use of oxen in ploughing
 
Soil fertility management
Soil fertility can be managed through several strategies including, organic fertilizers/manures, and inorganic or chemical fertilizers. 
Organic fertilizers/manures Farmyard manure (FYM) can be applied either alone at a rate of 4 tonnes per acre. When FYM is used in combination with inorganic fertilizers half the recommended rates should be applied.
 
Inorganic/chemical fertilizers Fertilizer recommendations are based on different agro-ecological zones and soil types. The main fertilizers used are Di-ammonium phosphate (DAP) at 50kg/acre (50kg bag/acre) (applied at planting), Calcium ammonium phosphate (CAN) at 92kg/acre (2 bags of 50kg each) topdressed when the plants are knee-high. However, farmers should follow the recommendations agreed during the KCEP validation workshop until further notice. 
 
Management of acid soils Liming is recommended for acidic soils. However, other fertilizers with a liming effect like MEA Mazao (100kg/acre), Mavuno basal (100 kg/acre) and Mavuno for topdressing (75 kg/acre) are recommended for acidic soils.
 
Planting Planting time
Planting should be done within the first two weeks of the onset of rains. It is recommended that there should be at least 30 cm of wet soil throughout the soil profile before sowing. While the hole is still moist, place two to three seeds in an evenly-spaced line in each hole, with one pip at each side and one in the on the other side. Cover the seeds using the soil heaped next to the hole to leave a level surface. Make sure no stones or heavy soil clods cover the seeds. Leave the mulch cover between the holes intact. Try to complete planting in a day to ensure an even germination and later, an even crop canopy, which will shade out any weed growth.
 
Spacing and plant population per hectare The recommended spacing and planting density of maize for different areas is as shown in table 3. 
Table 3: Recommended spacing and planting density of maize for different areas

Region

Spacing

Density (plants per            ha)

Highland

75x25cm 1 plant/hill (pure stand)

75 x 50cm 2 plants/hill (intercrop)

53,333

53,333

Medium

75 x 30cm 1 plant/hill (pure stand)

75 x 60cm 2 plants/hill (intercrop)

44,444

44,444

Dry land and coastal

90 x 30cm 1 plant/hill (pure stand)

90x 60cm 2 plants/hill (intercrop)

37,850

37,850

 
The appropriate planting depth varies from 2 to 10 cm, depending on the weather conditions and the moisture status of the soil. In the highland and medium areas where the soils are well-drained sandy-loam soils, planting depth of 2 to 3 cm is optimal, as deep seed placement retards germination and emergence of maize seedlings. In dry and coastal low land areas where the soil is dry and/or sandy, maize seed should be planted more deeply (5 to 10 cm). This enables the development of a deep root system to obtain the needed water and nutrients. Deep roots penetrate far into the soil and use moisture and nutrients from the deeper depths of the soil.
 
Weeding
Weeds reduce maize yields by competing for moisture, nutrients, space and light. Weeds are also an alternative host to pests and diseases. The most critical stage of weed competition in the life of a maize plant is during the first four to six weeks after emergence of the crop. The most common practice in weed management is hand weeding and use of herbicides. Some of the recommended practices include: hand weeding that should be done at least three weeks after emergence of the plants followed by a second weeding at knee high. Other recommended approaches include the use of a dense legume cover crop to suppress weeds for example lablab (Lablab purpureus), velvet bean (Mucuna pruriens) or sunhemp (Crotalaria juncea) and desmodium. Farmers should regularly scout their fields and uproot Striga weed early enough before the seeds are produced and diseased plants.
 
Crop rotation
Crop rotation is highly recommended to reduce build-up of maize diseases and insect pests. Rotation can be done with beans, cowpeas, peas or potatoes depending on the area. Rotation of maize with other cereal crops like sorghum and millet should be avoided, especially in case of maize lethal necrosis (MLN disease.