Pemberian kotoran sapi pada pertanaman jagung (Zea mays) perubahan beberapa sifat kimia dan fraksi fosfor inorganik pada ultisol Gunung Sindur

Abstract

Indonesia has wide area for acid upland soils. This upland soils are potential to develop as agricultural land. Soil order which dominantly occupied these acid upland is Ultisols. The Ultisols occupied about 24.3 % of the total acid upland soils. Acid upland soils in Indonesia have some limiting factors chemically and physically. Chemically, they have very low nutrient status and deficient in phosphorus (P), so that P fertilizer is recommended. Application of organic matter such as cow dung was expected to improve some chemical properties and P availability on acid upland soils. This reasearch was conducted in acid upland soil situated at Gunung Sindur District, Bogor Regency Cibadung Village. Analyses of soil chemical properties and the P inorganic fractions were held in the Laboratory of Chemistry and Soil Fertility, Department of Soil Science and Land Resource, Faculty of Agriculture, Bogor Agricultural University. The objectives of this research were to evaluate the effect of cow dung on the changes of some chemical properties and inorganic phosphorus fractions under maize cultivation. The rates of cow dung applied were 0, 10, 20, and 40 tons ha-1. The soil samples used were collected at the time before planting as initial soil properties, two weeks after incubation of manure application and harvest time in the rhizosphere area and between the plant rows The Application of cow dung increased soil pH significantly on two weeks after incubation and after harvest in rhizosphere area. These increases soil pH were followed by the decreases of exchangeable Aluminum. The Application of cow dung increased cation exchange capacity (CEC) significantly on two weeks after incubation but not significantly on that of after harvest in rhizosphere area and between plant rows as well. The application of cow dung increased soil organic carbon (C) on two weeks after incubation and on after harvest in rhizosphere area. The application of cow dung increased base saturation of the soil on two weeks after incubation and after harvest in rhizosphere area and between plant rows as well. The Application of cow dung increased resin-Pi and NaHCO3-Pi fractions on two weeks after incubation and on after harvest in the rhizosphere area and between plant rows as well. As for NaOH-Pi fraction, the application of cow dung only increased this P fraction on two weeks after incubation. Analyses of the P fraction changes (the content of the P fraction after harvest - two weeks after incubation) showed that the resin-Pi was negative values both in rhizosphere and between planting rows. This suggested the resin-Pi contents partly were transformed into other P fraction. The changes NaHCO3-Pi after harvest in rhiszosphere area and between plant rows were positive values. It suggested that partly resin-Pi contents were transformed into this fraction. From the evaluation of the changes on NaOH-Pi fraction which were interpreted as Al-P and Fe-P, the 3 contents of this P fraction of some samples decreased. This suggested that the NaOH-Pi fraction was not stable because it transformed to replenish if available P in soil solution depleted. Dynamics of P fractions that occurred after harvest were related to plant activities. From of the results, 40 tons ha-1 was recommended as ameliorant for Ultisols in Gunung Sindur.