Critical Level Determination of Phosphorus for Big Red Chili (Capsicum annuum L.) Growth on Soil in Java Island | Penentuan Batas Kritis Fosfor untuk Pertumbuhan Cabai Merah Besar (Capsicum annuum L.) pada Tanah di Pulau Jawa

English. One of the efforts that can be done so that the fertilization of phosphorus (P) accommodate the P needs of big red chili is by conducting soil analysis and determine the critical level of P in the soil related to the yield. The objective of this research was to determine the critical level of P for big red chili in Java Island. Soil samples were collected from 19 locations in Java Island. The soil P before planting of 19 locations was determined by three methods of P extraction namely Bray 1, Olsen, and Mehlich III. After soil P analyses, big red chili was planted in a pot containing 500 g of soil (oven-dry weight) from 19 locations where each location had 4 rates of P fertilization. The rates of P fertilization applied were 0, 55, 110, and 220 kg ha-1 P2O5. Urea and KCl were applied with the rate of 110 kg ha-1 and 180 kg ha-1 respectively as basal fertilizers. Plant biomass was harvested after the age of 4 weeks after planting. The effect of P fertilizer on growth parameters was evaluated using analysis of variance. The critical level of soil P was determined by the Cate and Nelson method. The results showed that P fertilization had a significant effect on plant height, fresh weight and dry weight of plants. Fertilization treatment of 220 kg ha-1 P2O5 resulted in the highest responses to plant growth parameters. The correlation test results showed that Bray 1, Olsen and Mehlich III extraction methods significantly and positively correlated with plant dry weight. The Olsen extraction method showed the highest correlation with plant dry weight (r=0.665). The critical levels of P in the soil for big red chili in Java determined by Bray 1, Olsen, and Mehlich III extraction methods, were 15 ppm, 40 ppm, and 50 ppm, respectively. Keywords: Bray 1, Cate and Nelson, extraction method, Mehlich, Olsen, soil analysis

Indonesian. Salah satu upaya yang dapat dilakukan agar pemupukan fosfor (P) sesuai dengan kebutuhan tanaman cabai merah besar ialah dengan melakukan analisis tanah serta menentukan batas kritis P di tanah yang dihubungkan dengan produksi. Tujuan dari penelitian ini adalah menentukan batas kritis P di tanah untuk tanaman cabe merah besar di Pulau Jawa. Contoh tanah diambil dari 19 lokasi yang tersebar di Pulau Jawa. Analisis P tanah sebelum tanam dilakukan dengan tiga metode ekstraksi P yaitu Bray 1, Olsen, dan Mehlich III. Setelah analisis P tanah, bibit cabe merah besar ditanam dalam pot yang berisi 500 g tanah berat kering mutlak untuk tiap lokasi dan tiap lokasi mempunyai 4 dosis pemupukan. Dosis pemupukan P terdiri dari 0, 55, 110, dan 220 kg ha-1 P2O5. Sebagai pupuk dasar juga diberikan pupuk urea dan KCl masing-masing dengan dosis 110 kg ha-1 dan 180 kg ha-1. Tiap tanaman dipanen biomassanya setelah berumur 4 minggu setelah tanam. Pengaruh pupuk P terhadap parameter pertumbuhan tanaman dievaluasi menggunakan analisis ragam. Batas kritis P tanah ditetapkan dengan metode Cate dan Nelson. Hasil menunjukkan bahwa pemberian pupuk P berpengaruh nyata terhadap tinggi tanaman, bobot basah dan bobot kering tanaman. Pemupukan 220 kg ha-1 P2O5 memberikan respon tertinggi terhadap parameter pertumbuhan tanaman. Hasil uji korelasi menunjukkan bahwa ketiga metode ekstraksi P tersebut berkorelasi positif dan nyata dengan bobot kering tanaman. Metode ekstraksi Olsen memiliki korelasi tertinggi dengan bobot kering tanaman (r = 0.665). Batas kritis P dalam tanah untuk tanaman cabai merah besar di pulau Jawa berdasarkan metode ekstraksi Bray 1, Olsen, dan Mehlich III masing-masing ialah 15 ppm, 40 ppm, dan 50 ppm. Kata kunci: analisis tanah, Bray 1, Cate dan Nelson, Mehlich, metode ekstraksi, Olsen