Response of Cacao Seedlings to Ameliorant, Phosphate Solubilizing Microbes, and Phosphate Fertilizers in Acid Soil

Abstract
Description
The growth of cacao in acid soils is commonly limited by some problems such as low available P and pH, and high Al saturation. Therefore, research is needed to solve the problem of coffee cultivation in acid soil. This study aimed to determine the effect of ameliorant, phosphate solubilizing microbes (PSM), and phosphate fertilizers (P) on the growth and nutrient uptake of cacao seedlings, and some acid soil properties. The study used a randomized block design with 3 factors and 3 replications. The first factor was ameliorant applications (without ameliorant, 10% organic fertilizer, 4% rice husk biochar, 4% rice husk biochar + 10% organic fertilizer). The second factor was PSM applications: without PSM, Burkholderia ambifaria (BPF) inoculants, and Aspergillus niger (FPF) inoculants. The third factor was P fertilizers applications (without Phosphate Rock (PR), 100, 200, and 400 mg P/kg of PR, and 400 mg P/kg of SP-36). The results showed that the applications of 4% rice husk biochar + 10% organic fertilizer + BPF or FPF inoculants increase the number of leaves by 77.9% and 69.2%, respectively, and increase the dry weight of shoot by 93.6 % and 101.9%, respectively. Phosphate rock application in media without organic fertilizer increases dry weight of shoots and roots of cacao seedlings, and the uptake of P, Ca, and Mg in shoots linearly in line with the increase of PR dose to 400 mg P/kg. Application of rice husk biochar significantly increased the acid phosphatase activity of growing media. Meanwhile, organic fertilizer increased the soil pH, acid phosphatase and available P activity, and decreased Al-dd growing media.
Pertumbuhan tanaman kakao di tanah kering masam umumnya dibatasi oleh beberapa kendala seperti rendahnya P tersedia dan pH, serta tingginya kejenuhan Al. Oleh karena itu, diperlukan penelitian untuk memecahkan masalah budidaya kopi di tanah kering masam. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian amelioran, mikrob pelarut fosfat (MFP), dan pupuk fosfat (P) terhadap pertumbuhan dan serapan hara benih kakao serta beberapa sifat tanah masam. Penelitian menggunakan rancangan acak kelompok dengan susunan perlakuan faktorial 3 faktor dan 3 ulangan. Faktor pertama adalah pemberian amelioran: tanpa amelioran, pupuk organik 10%, arang sekam padi 4%, dan arang sekam padi 4% + pupuk organik 10%. Faktor kedua adalah pemberian MPF: tanpa MPF, inokulan Burkholderia ambifaria (BPF), dan inokulan Aspergillus niger (FPF). Faktor ketiga adalah pemberian pupuk P (tanpa Fosfat Alam (FA), FA 100, 200, dan 400 mg P/kg, dan SP-36 400 mg P/kg). Hasil penelitian menunjukkan bahwa amelioran berupa arang sekam padi 4% + pupuk organik 10% + BPF atau FPF dapat meningkatkan jumlah daun masing-masing sebesar 77,9% dan 69,2%, serta meningkatkan bobot kering tajuk masing-masing sebesar 93,6% dan 101,9%. Pemberian pupuk FA secara tunggal pada media tanpa pupuk organik dapat meningkatkan bobot kering tajuk dan akar benih kakao, serta serapan P, Ca, dan Mg dalam tajuk secara linier sejalan dengan peningkatan dosis FA hingga 400 mg P/kg. Aplikasi amelioran berupa arang sekam padi meningkatkan aktivitas fosfatase asam media tanam. Amelioran berupa pupuk organik meningkatkan pH tanah, aktivitas fosfatase asam dan P tersedia, serta menurunkan Al-dd media tanam.
Keywords
Aspergillus niger; Burkholderia ambifaria; nutrient uptake; organic fertilizer; rice husk biochar, , Arang sekam padi; Aspergillus niger; Burkholderia ambifaria; pupuk organik; serapan hara,
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