Effect of tillage, biochar, poultry manure and NPK 15-15-15 fertilizer, and their mixture on soil properties, growth and carrot (Daucus carota L.) yield under tropical conditions
Taiwo Michael Agbede
Abstract
for the first and second growing seasons, respectively, compared with conventional tillage, which corresponded to a 11.1% increment for both years. Application of biochar alone, poultry manure alone and complementary application of NPK fertilizer, biochar and poultry manure decreased soil bulk density, penetration resistance, dispersion ratio and temperature and increased soil water content, porosity, aggregate stability and mean weight diameter whereas NPK fertilizer did not improve these soil physical properties. Biochar alone, poultry manure alone, NPK fertilizer alone and combined application of NPK fertilizer, biochar and poultry manure increased soil total N, available P, and exchangeable K, Ca and Mg concentrations compared with the control. Application of biochar alone improved soil pH, OC, K, Ca and Mg better than the NPK fertilizer. Poultry manure improved soil pH, OC, N, K, Ca and Mg better than the NPK fertilizer. Combined application of NPK fertilizer, biochar and poultry manure at sub-optimal rates gave higher soil N, P, K, Ca and Mg concentrations, higher plant, number of leaves, root length, root diameter and fresh carrot root yield compared with NPK fertilizer or biochar or poultry manure alone. Compared with control, NPK fertilizer alone, biochar alone, poultry manure alone and mixture of NPK fertilizer, biochar and poultry manure increased fresh carrot root yield by 43, 24, 46 and 76%, respectively. Reduced tillage in combination with NPK fertilizer, biochar and poultry manure gave the highest fresh carrot root yield. The results indicated that reduced tillage in combination with NPK fertilizer, biochar and poultry manure prove to be an effective and sustainable management strategy for improving soil quality and carrot yield than conventional tillage in combination with NPK fertilizer, biochar and poultry manure.