Author : Patmawati

Summary : Soil nutrient dynamics as affected by lime and phosphorus fertilizer at three different rates on acid soils; Annam clay, Alaminos silt loam, and Antipolo sandy clay loam were studied using peanut (ARACHIS HYPOGAEA L.) as test crop. The pot experiment was performed at the screenhouse of the Department of Soil Science, College of Agriculture, Central Luzon State University, Mu¤oz, Nueva Ecija on Februay - May 1990. The acidity of the soils were adjusted to pH 6.4 and pH 7.2, and phosphorus treatment involved 0, 60, and 120 kg P (subscript 2) O (subscript 5)/ha. Soil samples were collected at 45 and 109 days after planting (DAP) for analysis of pH, organic matter, exchangeable potassium (K), Calcium (Ca), Aluminum (Al), and available phosphorus (P). The best peanut yield was obtained from Antipolo sandy clay loam; Annam clay was the second best. Lime and phosphorus improved yield only in Antipolo sandy clay loam. In this soil, application of 120 kg P (subscript 2) O (subscript 5)/ha or pH adjustment to 6.4 significantly increased seed yield. Lime, phosphorus, or their combination increased soil pH in all soil types with lime exerting a more pronounced effect. Adjustment of pH to 6.4 increased available phosphorus only in Antipolo sandy clay loam. Lime or phosphorus increased exchangeable Ca at 45 DAP but subsidence to initial level occurred at 109 DAP. These amendments decreased exchangeable A1 such that at harvest only the unlimited treatments contained it. At 45 DAP, exchangeable K increased 4 - 5 times in all treatments in all soils except Alaminos silt loam. Added soil amendments did not affect N, P, Ca, and Magnessium concentration of the plant parts above the ground. Highest nutrient uptake occurred in Antipolo sandy clay loam. Available P and exchangeable Ca at 45 DAP were strongly correlated with dry matter yield and seed yield, whereas at 109 DAP only exchangeable Ca was correlated with seed weight.