EFFECTIVENESS OF ORGANIC AND REDUCED INORGANIC FERTILIZERS ON YIELD AND FODDER QUALITY IMPROVEMENT OF MAIZE IN WESTERN KENYA

Abstract

Maize remains a vital staple in Kenya, providing food for over 90% of the population and serving as the backbone of both food security and livestock nutrition. Despite its importance, maize production has declined in recent years, largely due to soil fertility depletion. This study, therefore, adopts the Integrated Soil Fertility Management (ISFM) principle of combining inorganic and organic P amendments to improve soil health and increase maize yields. The study leverages pressmud, a nutrient-rich residue from sugarcane processing that remains largely untapped in East Africa, despite its potential to improve soil health. Field trials were set up using a randomized complete block design to evaluate effect of sole application of pressmud in combination with cattle manure and reduced doses of P inorganic fertilizers in enhancing soil fertility, maize performance (grain yield and forage quality) and economic returns in two agro-ecological zones of western Kenya- Bungoma (LM2) and Kisumu (LM3). Soil samples were collected before and after the season to monitor changes in pH, organic carbon, nitrogen, phosphorus and

potassium. Agronomic data, including plant growth, grain yield, forage quality and cost- effectiveness, were also recorded and analyzed using ANOVA. The results showed that

pressmud applied at 30 kg P ha-1

(PM30) improved soil pH, available phosphorus and organic carbon, while cattle manure was more effective at boosting nitrogen content. The combination of 15kg Pha-1

from both organic and inorganic sources (TSP15+PM15 or TSP15+CM15) consistently resulted in grain yields exceeding 4.4 tons per ha, improved plant growth, crude protein in fodder and showed superior profitability while forage dry matter yields peaked under TSP10+PM10+CM10 in Bungoma and TSP22.5+PM7.5 in Kisumu. While not all treatments enhanced every aspect of forage quality most improved digestibility and maintained acceptable fiber levels but however, fodder from Bungoma showed slightly inferior acid detergent fiber (ADF) content. Based on these findings, farmers in similar regions are encouraged to use PM30 for improving phosphorus availability or CM30 for boosting nitrogen. To maximize grain yields and profitability, TSP15+CM15 (75kgTSP+3.06 t per ha of cattle manure) is recommended which also supports better fodder quality. Further research is needed in other agro-ecological zones and to better understand the factors behind reduced fodder quality.