摘要
Soil acidification and phosphorus deficiency are a major constraint to crop production in tropical soils. Use of conventional liming materials is associated with some limitations viz： inability to solely improve nitrogen and available phosphorus in soils, loss of soil organic carbon and soil aggregate stability. Liming and fertilizer potentials of leaves from three plant materials （Tithonia diversifolia （TL）, Imperata cylindrica （SG） and Gliricidia sepium （GL）） widely growing in Ogbomoso, southwest Nigeria, were tested under incubation condition. Each of the plant material was applied at.the rate of 10 t·hm-2 with and without 50% concentration of NPK 15 ： 15 ： 15-urea mix in 500 g acidic soiL Sole lime applied at 1 t·hm-2, sole NPK 15 ： 15 ： 15 applied at 60 kg·hm2 mixed with urea at 60 kg N· hm2 and an unamended soil were compared in completely randomized design in three replicates. The treated soils were incubated for 12 weeks. Thereafter, maize seeds were raised in each pot for a period of 3 weeks. Data coUected were subjected to analysis of variance. Regression analysis was used to predict contributions of increased soil pH in plant material treated soils to exchangeable A1, H, dry root weight of maize and available phosphorus. Results indicated that sole plant materials were the order SG〉TL〉GL significantly （P〈0.05） reduced exchangeable acidity compared to unamended and sole NPK. Sole NPK had the highest exchangeable acidity （4.7 cmol·kg-1） compared to unamended soil （3.3 cmol·kg-1） and sole lime （2.7 cmol·kg-1）. Application of sole Tithonia diversifolia increased available phosphorus by 214% and 97% compared to unamended and sole NPK treated soils respectively. Sole plant materials increased maize root weight by 33% compared to sole NPK. Increasing soil pH at harvesting in plant material treated soils significantly reduced exchangeable H and A1. Soil pH was responsible for up to 33% and 53% reductions in exchangeable Al and H, respectively. This culminated into up to 22% increases in dry root weight of maize seedling. Present results showed ability of the plant materials tested to ameliorate soil acidity and improved soil available phosphorus. The plant materials should be explored for using as green manure and composting feedstock. It will go a long way to reduce high dosage use of conventional liming and fertilizer materials on acidic nutrient degraded soils.
Soil acidification and phosphorus deficiency are a major constraint to crop production in tropical soils. Use of conventional liming materials is associated with some limitations viz： inability to solely improve nitrogen and available phosphorus in soils, loss of soil organic carbon and soil aggregate stability. Liming and fertilizer potentials of leaves from three plant materials （Tithonia diversifolia （TL）, Imperata cylindrica （SG） and Gliricidia sepium （GL）） widely growing in Ogbomoso, southwest Nigeria, were tested under incubation condition. Each of the plant material was applied at.the rate of 10 t·hm-2 with and without 50% concentration of NPK 15 ： 15 ： 15-urea mix in 500 g acidic soiL Sole lime applied at 1 t·hm-2, sole NPK 15 ： 15 ： 15 applied at 60 kg·hm2 mixed with urea at 60 kg N· hm2 and an unamended soil were compared in completely randomized design in three replicates. The treated soils were incubated for 12 weeks. Thereafter, maize seeds were raised in each pot for a period of 3 weeks. Data coUected were subjected to analysis of variance. Regression analysis was used to predict contributions of increased soil pH in plant material treated soils to exchangeable A1, H, dry root weight of maize and available phosphorus. Results indicated that sole plant materials were the order SG〉TL〉GL significantly （P〈0.05） reduced exchangeable acidity compared to unamended and sole NPK. Sole NPK had the highest exchangeable acidity （4.7 cmol·kg-1） compared to unamended soil （3.3 cmol·kg-1） and sole lime （2.7 cmol·kg-1）. Application of sole Tithonia diversifolia increased available phosphorus by 214% and 97% compared to unamended and sole NPK treated soils respectively. Sole plant materials increased maize root weight by 33% compared to sole NPK. Increasing soil pH at harvesting in plant material treated soils significantly reduced exchangeable H and A1. Soil pH was responsible for up to 33% and 53% reductions in exchangeable Al and H, respectively. This culminated into up to 22% increases in dry root weight of maize seedling. Present results showed ability of the plant materials tested to ameliorate soil acidity and improved soil available phosphorus. The plant materials should be explored for using as green manure and composting feedstock. It will go a long way to reduce high dosage use of conventional liming and fertilizer materials on acidic nutrient degraded soils.
