Residual effect of nutrient integration on some selected soil chemical properties of the guinea savanna agro-ecological zone of Nigeria.

Abstract

The effects which integrated Nutrients (organic, inorganic and Biological Nitrogen fixer) had on soil chemical properties were evaluated after the conduct of the main experiment using maize as the experiment unit in 2008 and 2009. Treatments and treatment rates used were as follows. Poultry manure (0, 30 and 6 tha -1 ), NPK 20-10-10 (0, 150 and 300 Kg ha -1 ), cowpea (ITAS EARLY). Treatments were combined pair-wise to give ten treatments. The experiments were conducted at the University of Agriculture, Makurdi, Teaching and Research Farm. The experimental design used was Randomized Complete Block Design (RCBD) and replication was done thrice. Plot size measured 3 m X 4 m with an alley of 1 m between blocks and 0.5 m between plots. Maize was planted on rows spaced 75 cm apart and 50 cm within the row, three seeds were planted per hole and latter thinned to two plants per stand at 2 weeks after planting (2 WAP), this gave a total plant population of 53,333 plants per hectare. Before the on set of the experiment soil samples to a depth of 15 cm were collected to determine the physical and chemical properties of the soil. Soil samples were also analyzed at harvest in 2008 and 2009 to determine the chemical properties of the soil as affected by various treatment combinations. Integrated application of organic manure + NPK 20 - 10 - 10 + Cowpea (ITAS EARLY) have positive impact (P < 0.05) on soil organic manure (SOM), soil Nitrogen P, soil exchangeable cations in terms K, Ca, Mg and Na. In 2009, the combination of 6 t ha -1 poultry manure + 300 kg ha -1 NPK 20 - 10 - 10 gave the highest in terms of exchangeable bases K, Ca, Mg, Na (0. 42, 4.01, 3.20 and 0.64 c mol kg -1 respectively). For soil fertility sustenance 6 t ha -1 poultry manure + 300 kg ha -1 NPK 20 - 10 - 10 and cowpea