Integration of manure and mineral fertilizers among smallholder farmers in Kenya: a pathway to sustainable soil fertility management and agricultural intensification (Published)
Combination of mineral fertilizers and manure has been proposed as the sustainable approach of soil fertility management. This study evaluates the use of these two soil fertility practices. Data for this study was obtained through a survey conducted between January-March 2019 with 106 farmers. Results show that the proportion of farmers who used manure and inorganic fertilizer was 93.4% in each case. About 90% of the farmers used both fertilizer and manure. Farmers accessed fertilizers mostly through direct purchase from the local market (73.9%). Most of the manure is obtained on-farm (84.8%). About 67% of farmers used fertilizer both for planting and top dressing. However, only 20% of the farmers used fertilizer every season. Low income, low literacy, lack of soil fertility management skills, small land sizes, low livestock units, limited and declining capacity of agricultural extension explain the low investment in soil fertility management. Timely delivery of low-cost, high quality fertilizer is of paramount concern. Glaring loopholes undermining the efficiency of the government subsidy program have to be addressed. Farmers’ capacity building is necessary to ensure high quality manure. Policy and institutional support are necessary to reverse the declining capacity of soil science research and agricultural extension.
Effect of Siam Weed (Chromolaena Odorata L.) Residues, Phosphorus Fertilizer and Manure Application Time on Soil Properties, Growth and Root Yield of Sweet Potato in Acidic Soil (Published)
Field experiment was conducted at Lower Niger River Basin Development Authority, Ejiba in 2016 and 2017 cropping seasons to investigate the effect of Siam weed (Chromolaena odorata L.) residues, phosphorus fertilizer and manure application time on soil properties, growth and root yield of sweet potato in acidic soil. Treatments constituted of 4 x 4 factorial arrangements in a Completely Randomized Block Design. Four levels of amendments which were 5t/ha Chromoleana odorata residues, 60 kg/ha phosphorus, 2.5t/ha Chromoleana odorata residues plus 30 kg/ha phosphorus, No Chromoleana odorata residue and no single superphosphate fertilizer (control) and four levels of time of application of the residues which were three (3) weeks before planting (3WBP), manure application at planting (ATP), manure application at three (3) weeks after planting (3WAP) and manure application at six (6) weeks after planting (6WAP). Data on soil pH, growth and yield parameters were collected and subjected to analysis of variance. Significantly different means were separated using Duncan Multiple Range Test at 5% level of probability. The results indicated that soil acidity increased in plots with mineral fertilizer alone in both years. Plot with combined application of Chromolaena odorata residues and phosphorus at reduce rate were better in all the growth and yield characters compared with plots with either Chromolaena odorata residues or phosphorus fertilizer alone. The least values of vine length shoot weight, number of primary branches, and number of tubers per plant, weight of tubers per plant and tuber weight per land area occurred in the control plots. When Chromolaena odorata residues were applied 3 weeks before planting, maximum growth and yield characters were observed. Manure Applied at three (3) weeks before planting gave best growth and yield of sweet potato in this experiment. Application of Chromolaena odorata residues at 2.5 t/ha combined with phosphorus at 30 kg/ha is therefore recommended to the sweet potato farmers for maximum production of sweet potato. Also, Chromolaena odorata residues should be applied into the soil three (3) weeks before planting as it gives maximum values performance parameters.