Abstract:
Increased food production could be achieved in degraded soils by expanding the land area through proper soil management and utilization of abundant wastes in our societies to increase yields per unit area as well as to improve soil fertility. This study investigated whether tillage and amendments can improve the physical and chemical properties of an alfisol in southwestern Nigeria and how it affects the nutrient use efficiencies, growth and yield performances of white and yellow trifoliate yams over two years. The trials were carried out in 2013 and 2014 farming seasons at two locations simultaneously: (i) at the Teaching and Research Farm of the Ekiti State University (EKSU), Ado-Ekiti and (ii) at the Teaching and Research Farm of the Federal University of Technology Akure (FUTA). Treatments were 4 X 4 factorial combinations of Tillage methods and amendments tested on two varieties of trifoliate yam. Traditional tillage methods were Heap, Ridge, Bed and Flat which were amended with 20 t/ha Poultry Manure, 20 t/ha Ash, 400 kg/ha NPK and an unfertilized Control CTRL (where no form of amendments was applied) while the varieties were White and Yellow. Treatments were replicated three times and were arranged in a Randomized Complete Block Design (RCBD). Results showed that Flat significantly (p ≤ 0.05) had higher bulk density, organic C, N, P, K, Ca, and Mg values but Heap had higher growth and yield values than other land preparation methods. Compared with Ridge, Flat and Bed methods when averaged across years, Heap increased tuber yield by 25%, 42% and 31% for white trifoliate yam and 16%, 34% and 25% for yellow trifoliate yam in Ado Ekiti. Similarly, Heap also increased tuber yield by 12%, 19% and 18% for white trifoliate yam and 7%, 15% and 11% for yellow trifoliate yam in Akure. However, heap and ridge methods had significant higher Phosphorus use efficiency (PUE) than Flat and Bed methods. The use of amendment significantly (p ≤ 0.05) increased the soil pH, Organic C, N, P, K, Ca, and Mg concentrations when compared with CTRL (no amendments). Ash amended soils had higher pH, K, Ca, Mg concentrations, growth and yield values than other treatments. Nutrient use efficiencies (NUE) were also significantly (p ≤ 0.05) higher in ash amended soils than other treatments. Compared with poultry manure, NPK and CTRL, averaged across years, Ash amendment increased tuber yield by 15%, 36% and 66% for white trifoliate yam and 22%, 19% and 25% for yellow trifoliate in Ado–Ekiti while tuber yield increased by 12%, 26% and 27% for white trifoliate and 3%, 26% and 25% for yellow trifoliate in Akure. Interaction of tillage methods and amendments showed increased soil pH, nutrient use efficiencies, growth and yield values in the combination of heap methods and ash amendment than other treatment combinations. Synergistic use of heap method and ash amendment at 20 t/ha was most effective for sustainable management of soils and for improving agronomic productivity of trifoliate yam.
