Nitrolimegation: A Nutrient-In-Water Resource for Sustainable Crop Production on ‘Acid Sands’ of Southern Nigeria

Abstract

The effects of a low-external-input soil fertility enhancement solution – hereafter termed ‘nitrolimegation’ were investigated as a more convenient strategy for application of nitrogen and calcium in the “Acid Sands” soils of south-eastern Nigeria. Two types of nitrogenous fertilizer sources [Urea and liquid pig manure (LPM)] and two types of lime [limestone-CaCO₃ and slake lime-Ca(OH)₂] were employed variously at the following levels: Urea [CO (NH₂)₂] 0, 40, 50, 80, 100, 120, and 150 kg/ha; lime 0, 0.1, 0.3, 0.5, 1.0, 5.0, and 10.0 metric tonnes per hectare (t/ha) and LPM 0, 30, 60, 90 and 120 t/ha, arranged factorially and laid out in randomized complete block design (RCBD). The results indicated that combining lime at 9 t/ha and LPM at 90 t//ha in irrigation water had significant (P<0.01) positive effects on the soil fertility status and growth of the test crop (Okra- Abelmoschus esculentus). When urea combined with slake lime, it offset acidity and provided nutrient balance in the Acid Sands of Calabar; total nitrogen was significantly (P<0.01) boosted from 0.05 to 0.11 %, base saturation (BS) from 46 to 62 % and exchange acidity was reduced from 2.93 to 1.35 cmol/kg. Combining urea (46-0-0) at 80 kg/ha with lime (CaCO₃) at 5 t/ha raised the soil pH from 4.4 to 7.1. Exchange acidity was reduced from 0.8 cmol/kg to negligible value but electrical conductivity was improved from 170.7 to 291.9 μS/cm. When LPM and lime were combined, organic carbon was increased from 2.75 to 2.93%, BS was increased from 46.72 to 75.19 %, and pH was raised from 6.0 to 6.73. Plant height was increased from 9.5 to 16.9 cm while mean number of leaves was also increased from 5.6 to 6.3 only with lower level of lime (3 t/ha) and LPM at 90 t/ha. Of the nitrogen and calcium sources, LPM and limestone y were better at 120 t/ha and 9 t/ha, respectively, to offset soil acidity, boost nutrient availability and provide balanced supply to arable crops grown on the Acid Sands.

Keywords: Nitrolimegation, Nitrogen fertilizer, Liming, Liquid pig manure, Acid Sands, Okra (Abelmoschus esculentus L. Moench).