Evaluation of organic and inorganic sources of phosphorus for smallholder maize production in Kisii,South west Kenya
2002
Obaga, S.O.(KARI-Regional Reseach Kisii, Kenya) | Maobe, S.N.(KARI-Regional Reseach Kisii, Kenya) | Makini, F.(KARI-Regional Reseach Kisii, Kenya)
Widespread low soil phosphorus levels in the Kisii highlands contribute towards low crop yields, particularly maize. Serious soil erosion, continuous cropping, removal of crop residue as woodfuel and livestock feed as well as burning of stover and limited use of inorganic fertilisers are the major causes of soil fertility decline in the area. Participatory on-farm work was done in three villages to assess the usefulness of applying different sources of phosphorus in addressing the problem using maize as the test crop. Diammonium phosphate (DAP) and Minjingu phosphate rock (RP) were sources of inorganic phosphorus while Farm Yard Manure (FYM) and nthonia diversifolia biomass were sources of organic nitrogen and phosphorus. Results from two cropping seasons in 1998 indicated that combining either good quality FYM at 10 t ha-I or 1-2 t ha- DM of T. diversifolia with 200 kg ha-I RP gave comparable maize yields to application of the recommended agronomic rate of 60 kg Nand 60 kg P20s ha-I for maize. Since Minjingu RP is cheaper than DAP, farmers preferred combining the organics and RP to the use of DAP and CAN in maize production.
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