Maize productivity as influenced by organic inputs and mineral fertilizer in a Nitisol soil in Meru South District
Mugwe, J. N.
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Declining land productivity is a major problem facing smallholder farmers in Kenya today. This decline primarily results from a reduction in soil fertility caused by continuous cultivation without adequate addition of external nutrient inputs. Improved fertility management combining organic and mineral fertilizer inputs can enable efficient use of the inputs applied and increase overall syste productivity. Field trials were established at two sites with different soil fertility status in Mucwa with the aim of determining the effects of various organic sources (tithonia, mucuna, calliandra and manure) and their combinations with mineral N fertilizer on maize grain yield and soil chemical properties. Sole tithonia and sole calliandra treatment generally recorded the highest maize grain yields for Mucwa poor and Mucwa good sites, respectively. Generally the maize grain yields were lower in the treatments with fertilizer alone compared to the treatments with organics in the two sites in the seven cropping seasons. There was a general decline in soil chemical properties over the seasons, even with the seasonal input application in both sites. Manure was superior in terms of improving soil chemical properties for instance, it supported an increase in soil pH, magnesium, potassium, calcium and nitrogen.