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Field experiments were conducted at Owo, southwest Nigeria to select organic fertilizer treatments most suitable for sustaining high soil fertility and yam productivity on a nutrient-depleted tropical Alfisol. Eight organic fertilizer treatments were applied at 20 t ha 71 with a reference treatment inorganic fertilizer (NPK 15-15-15) at 400 kg ha 71 and natural soil fertility (control), laid out in a randomized complete block design with three replications. Results showed that organic fertilizers significantly increased (p ¼ 0.05) tuber weight and growth of yam, soil and leaf N, P, K, Ca and Mg, soil pH and organic C concentrations compared with the NSF (control). The oil palm bunch ash þ poultry manure treatment increased tuber weight, vine length, number of leaves and leaf area of yam by 66, 25, 21 and 52%, respectively, compared with inorganic fertilizer (NPK) and 37, 22, 19 and 44%, respectively, compared with poultry manure alone. Sole or mixed forms of organic fertilizers showed significant improvement in soil physical conditions compared with IF (NPK) and NSF (control). Synergistic use of oil palm bunch ash þ poultry manure at 10 t ha 71 each was most effective for sustainable management of soils and for improving agronomic productivity of yam.

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A laboratory experiment was carried out at Cocoa Research Institute of Nigeria, Ibadan to evaluate the nutrientrelease pattern of neem fortified cocoa pod husk developed for use as organic fertilizer materials. Cocoa Pod Husk(CPH), Neem Leaf (NL), Neem Seed (NS), CPH + NL (90:10), CPH + NL (80:20), CPH + NS (90:10) and CPH +NS (80:20) were separately applied at the rate of 100 kg N ha-1 into 50 g soil placed in plastic cups. There were sixsampling periods (2, 4, 8, 12, 16, and 20 weeks) after treatment application. Soil N (Kjeldahl), P (Bray 1), K (1 NNH4OAc pH 7) and pH (soil:water ratio 1:2) were determined at each sampling period. The result showed that theorganic materials had significant effect in raising the pH of the soils compared to unamended soil. Neem fortifiedCPH significantly (P < 0.05) increased nitrogen release higher than control at 8, 12 and 16 weeks after application.Phosphorus release was significantly higher in soil treated with CPH, NL, NS and neem fortified CPH than thecontrol at 20 weeks after application. CPH and neem fortified CPH enhanced K release better than NL and NSapplied separately across the incubation periods. Neem leaf and seed powder with higher N content than CPH is aprecursor of N- release into the soil shortly after incorporation.[How to Cite: Ogunwole OM, GO Adeoye, O Fagbola and JS Ogeh. 2012. Studies on Nutrient Release Pattern of Neem Fortified Cocoa Pod Husk Fertilizer in an Alfisol. J Trop Soils 17 (2) : 129-134. Doi: 10.5400/jts.2012.17.2.129]  [Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.2.129]

A field experiment was conducted on an Arenic paleudult in the rainforest zone of Southern Nigeria to determine the response of an improved variety of peanut (Arachis hypogea L. var. Samnut 23) to phosphorus, under different land preparation methods. Selected land preparation methods were “slash and burn” (SB) and “slash and mulch” (SM), and the phosphate fertilizer rates were 0, 30, 60, 90 and 120 kg P ha-1.  The experiment was laid out as a randomized complete by block design. Each land preparation was divided into plots. Macro- and micro nutrient contents of peanut plants were determined, and the growth and yield components were also assessed. Results showed that the pre planting soil analysis for the SB management had a pH of 5.77, N (1.8 gkg-1), P (2.05 mgkg-1) and K (0.11cmol (+) kg-1), while that of the SM had a pH of 5.95, N (0.9 g kg-1), P (0.86 mg kg-1) and K (0.07cmol(+)kg-1).  Plant height was not significantly different (pd” 0.05) in the land preparation methods, but leaf area was significantly different. However, plant height and leaf area responded better under the SB treatment with 90 kg P ha-1 rate of phosphorus fertilizer than the SM treatment under the same rate. Fresh pod weight of 908.6kg ha-1 and dry pod weight of 558.0kg ha-1 was obtained at 60 kg P ha-1 under the SB treatment and was significantly different from all other treatments including the SM. Significant differences were also observed in the nutrient concentrations of leaves and roots. Highest leaf phosphorus content (3.502 mg kg-1) was recorded at 90kg P ha-1 in the SM treatment while the highest nutrient content of P in the roots (0.272 mg kg-1) was recorded at 30 kg P ha-1 also in the SM treatment. However, the SB treatment recorded the highest peanut seed pods / shell at 60 kg P ha-1. Generally, phosphorus fertilization under the SB management practice gave better results than the SM management practice.Keywords: groundnut, land preparation, phosphorus fertilization, Slash and burn, slash and mulch    [How to Cite: Joseph SO and RO Oyibo. 2014. Phosphorus Fertilization Under Different Land Preparation Methods and Performance of Groundnut (Arachis hypogea L.) in Rainforest Zone of Southern Nigeria. J Trop Soils 19(1): 1-7. Doi: 10.5400/jts.2014.19.1.1]