Short- and long-term effects of sparingly soluble phosphates on crop production in two contrasting Nigerian Alfisols

Abstract

The effectiveness of Sokoto and Ogun rock phosphates (RP) as substitutes for the conventional phosphorus (P) fertilizer sources in the production of tomato (Lycopersicon esculentum) and okra (Hibiscus esculentus) were evaluated using single super-phosphate (SSP) as reference. Their residual effects were also investigated using rice (Oryzae sativa) and soybean (Glysine max). The two experiments were 2 × 2 × 4 factorial combinations with completely randomized design (CRD) involving two crops, two soils, three P-fertilizer sources and a control. The treatment combinations were replicated four times to give a total of 64 pots, each containing 5 kg of either a slightly acid (pH 6.3) alfisol (Typic Paleudalf) A, from Abeokuta (rainforest ecological zone) or a medium acid (pH 5.9) alfisol (Oxic Paleustalf) B, from Zaria (southern Guinea savanna zone). The soils represent a wide range of Nigerian soils with medium to low P-availability and cultivated to various food and economic crops. The rock phosphates (particularly SRP) were more efficient than SSP in soil A but had less than 50% relative agronomic efficiency (RAE) in soil B, especially when tomato was the test crop. They also had higher RAE in soil A than in soil B when okra was grown, though the efficiency was not as high as that of the reference fertilizer. In the slightly acid alfisol (A), ORP was less efficient than SRP whereas it had 47.8% RAE compared with 34.9% RAE for SRP in the medium acid soil. In the second cropping, the soil from the rainforest zone still produced greater biomass than soil B while soybean gave more biomass than rice. The results confirmed that, apart from crop species to be grown, organic matter and clay contents as well as pH of soils should be considered for efficient utilization of the sparingly soluble phosphates for both short-and long-term effects in crop production.

Comparative Effects of Soil Amendments on Phosphorus Use and Agronomic Efficiencies of Two Maize Hybrids in Acidic Soils of Molo County, Kenya

“…The agronomic effectiveness of PRs depends not only on inherent factors, but also on plants/crop genotypes utilized [1]. Akinrinde and Okeleye [75] observed that rock phosphates had less than 50% relative agronomic efficiency (RAE) in an oxic Paleustalf especially when tomato was the test crop. They reported that crop species to be grown as well as pH of soils should be considered for efficient utilization of the sparingly soluble phosphates for both short-and long-term effects in crop production.…”

Effects of Bradyrhizobium japonicum and Phosphorus Supplementation on the Productivity of Legumes

“…The low yields are pronounced in grain legumes and are often associated with low P levels in the soil and reduced N 2 -fixation. Although legume yields can potentially improve from the application of moderate levels of chemical fertilizers, these inputs are rarely used either because of the high cost [7,8], lack of awareness of the economic returns from such cultural practice, or both. Supplementing legumes with N and P has great potential for increasing yields, as they do not only promotes plant growth but also enhances symbiotic establishment for increased N 2 fixation [9] and hence high yield.…”

Growth and Yield Response of Soyabean (<i>Glycine max</i> Merr.) to Organic and Inorganic Fertilizer in Edo Rainforest of Nigeria

“…Application of mineral fertilizer as soil fertility management under intensive continuous cropping is no longer feasible due to non availability, high cost where available and the numerous side effects on the soil [5]. Farmers using mineral fertilizer for years usually notice signs of soil exhaustion shown by sick appearance of the plant, leaf discolorations, retarded growth and low yield.…”