Dinamika Beberapa Fraksi Kalium Pada Inceptisol Di Kabupaten Brebes Selama Inkubasi Pupuk Kandang Sapi

Abstract

Tanah Inceptisol di Kabupaten Brebes banyak digunakan secara intensif untuk budidaya bawang merah dan memiliki kandungan kalium (K) yang relatif tinggi akibat penggunaan pupuk secara intensif. Penelitian ini bertujuan untuk mengetahui dinamika beberapa fraksi K dan sifat kimia tanah selama inkubasi pupuk kandang sapi pada Inceptisol asal Kabupaten Brebes. Penelitian menggunakan Rancangan Acak Lengkap (RAL) dengan 4 perlakuan dosis pupuk kandang sapi 0, 10, 20, dan 35 t/ha pada waktu inkubasi 0, 2, 4, dan 8 minggu, dengan tiga ulangan. Parameter yang dianalisis meliputi K2O HCl 25%, K-dd (K-dapat ditukar), K-larut air, C-organik, pH H2O, pH KCl, kapasitas tukar kation (KTK), Ca-dd, dan Mg-dd. Hasil penelitian menunjukkan bahwa pemberian pupuk kandang sapi tidak berpengaruh nyata terhadap K2O HCl 25%, dan K-larut air kecuali pada waktu inkubasi ke-0, tetapi berpengaruh nyata terhadap K-dd pada minggu ke-2 dan 4 inkubasi. K2O HCl 25% cenderung menurun selama inkubasi, sedangkan K-dd meningkat sampai mencapai nilai tertinggi pada minggu ke-4, dan K-larut air cenderung meningkat hingga minggu ke-8. Peningkatan K-dd dan K-larut air juga terjadi pada perlakuan kontrol (tanpa pupuk kandang sapi), yang mengindikasikan adanya pelepasan dan redistribusi K asli tanah selama inkubasi. Perlakuan pupuk kandang sapi berpengaruh nyata terhadap C-organik dan pH tanah. Kadar C-organik meningkat seiring waktu inkubasi, terutama pada dosis tinggi, sedangkan pH menurun pada awal inkubasi. Oleh karena itu, hasil penelitian menunjukkan bahwa dinamika K-dd dan K-larut air selama inkubasi tidak hanya dipengaruhi oleh kontribusi K dari pupuk kandang sapi, tetapi juga berasal dari pelepasan dan redistribusi K asli tanah dari pool K yang sukar tersedia.

Inceptisol soils in Brebes Regency are extensively used for shallot cultivation and have relatively high potassium (K) content due to intensive fertilizer application. This study aimed to determine the dynamics of several K fractions and soil chemical properties during the incubation of cattle manure on Inceptisol soils from Brebes Regency. The study employed a completely randomized design (CRD) with four treatments of cattle manure application rates (0, 10, 20, and 35 t/h) at incubation periods of 0, 2, 4, and 8 weeks, with three replications. The parameters analyzed included K2O (25% HCl), exchangeable K, water-soluble K, organic C, pH (H2O), pH (KCl), cation exchange capacity (CEC), exchangeable Ca, and exchangeable Mg. The results showed that the application of cattle manure had no significant effect on 25% HCl K2O and water-soluble K except at the 0-week incubation period, but had a significant effect on exchangeable Kat weeks 2 and 4 of incubation. K2O (25% HCl) tended to decrease during incubation, while exchangeable K increased until reaching its highest value in the fourth week, and water-soluble K tended to increase until the eighth week. Increases in exchangeable K and water-soluble K also occurred in the control treatment (without cattle manure), indicating the release and redistribution of native soil K during incubation. Cow manure treatments had a significant effect on organic C and soil pH. Organic C content increased over the incubation period, particularly at high doses, while pH decreased at the beginning of incubation. Therefore, the results of the study indicate that the dynamics of exchangeable K and water-soluble K during incubation are influenced not only by the contribution of K from cattle manure but also by the release and redistribution of soil-native K from the poorly available K pool.