Field Management

Fertilizer application

When other husbandry practices are properly done, the use of fertilizers increases yield. Fertilizer recommendations are made when soil analysis has been done. The use of fertilizers in maize production is economic only where improved varieties are used.

Phosphate fertilizers should be applied in the planting holes in the time of sowing while nitrogen fertilizers should be top dressed when maize is knee high (45-60 cm high).

Broad fertilizer recommendations for maize growing areas in Kenya

Area or district

Soil condition

Time of planting (amount per acre)

Top dressing

(amount per acre)

Trans Nzoia, Nandi, Uasin Gishu, Kericho

Newly cultivated forest soils

36 Kg TSP

36 Kg DAP

62 Kg CAN or ASN

40 Kg CAN or ASN

Old cultivated fertile soils

52 Kg TSP

52 Kg DAP

92 Kg CAN or ASN

58 Kg CAN

Moderately fertile soils

70 Kg TSP

70 Kg DAP

124 Kg CAN or ASN

74 Kg CAN

Soils of low fertility

1 Ton FYM

36 Kg DAP + 1 ton FYM

62 Kg CAN or ASN

40 Kg CAN or ASN

Acidic soils of Uasin Gishu

3 tons FYM

Kisii highlands and Central Kenya

52 Kg TSP

52 Kg DAP

92 Kg CAN or ASN

58 Kg CAN

Nyanza & Western Province (Except on black cotton soils and Kisii Highlands)

36 Kg DAP

80 SSP

40 Kg CAN

62 Kg CAN

Medium Zones of central province

100 Kg NPK 20:20:0

Marginal areas of Eastern province

60 kg – 80 Kg NPK 20:20:0

Coastal Lowlands

Sandy Soils

100 Kg NPK 20:20:0

44 Kg DAP

3 Ton FYM

48 Kg ASN

Method of application

When planting manually, is recommended to place a teaspoonful or soda bottle cap of fertilizer into each planting hole. Thoroughly mix the fertilizer with the soil and then place the seed. Under mechanical planting well calibrated planters with fertilizer hoppers are used.

Top dressing- in high rainfall areas the fertilizer is applied in two splits. 1st split is done 6 weeks after sowing and 2nd split is done 10-15 days later or just before tasseling. In low rainfall areas fertilizer is applied once.

Top dressing is done when the soils are moist, apply 1 teaspoonful of fertilizer at the base of each plant in a ring[approximately 15 cm radius] or along the row 15 cm away from the plant.

Weeding

Weeding can be done mechanically/manually or by use of herbicides.

When done manually, first weeding is done within the 3rd week after planting or depending on the growth of weed in the area. The field should be kept weed free till maize tasseling after which their presence might not cause crop loss.

In pure stand, herbicides can be used to effectively control weeds. Instructions should be followed carefully to ensure effectiveness.

Rates of applications:

  • 2,4-D : 0.75 litres/ha – post emergence

  • Lasso/Atrazine 2-3 litres/ha – pre emergence

  • Primagram 3 litres/ha – pre emergence

Striga weed [Striga hermonthica]

In heavy infestation, Striga weed can cause losses between 50%-100%. It is common in Coast, Nyanza and parts of Western Province.

Maize Figure 2: Striga in a maize field

Maize Figure 2: Striga weed in a maize field

Control

  • Uproot the weed as it flowers to avoid seeding.

  • High FYM application{25 ton per ha]

  • Use of fertilizers, particularly Ammonia type e.g. ASN

Maize Figure 3: Striga weed at flowering stage

Maize Figure 3: Striga weed at flowering stage

  • Rotation with crops like cotton, sunflower, soya bean and groundnuts

  • Intercrop with Desmodium (Desmodium uncinatum) to suppress the parasitic witchweed Striga.

Thinning and Gapping

  • Gapping is done to replace ungerminated seeds immediately after germination is complete.
  • Thinning is done when maize has grown to height of 15 cm by removing the weak and deformed seedlings to leave the desired number of seedlings per hole.