Kombinasi Pyrolyzed Reject Coal dan Pupuk Kandang Ayam Sebagai Amelioran Tanah Sawah dan Pengaruhnya Pada Produksi Padi di Kabupaten Karawang

Abstract

Padi merupakan pangan utama masyarakat Indonesia. Produksi padi Indonesia dan Jawa Barat menurun 2,93% dan 8,5%, sedangkan Kabupaten Karawang sebagai sentra padi mengalami penurunan produktivitas 6,67% akibat penurunan kualitas tanah dan bahan organik. Penggunaan bahan organik seperti pupuk kandang ayam berpotensi memperbaiki kesuburan tanah dan meningkatkan efisiensi pupuk anorganik. Limbah batu bara berupa reject coal berpotensi dimanfaatkan sebagai pembenah tanah, namun penggunaannya dalam bentuk hasil pirolisis pada tanah sawah masih terbatas. Reject coal hasil pirolisis mampu meningkatkan pori tanah, retensi hara dan habitat mikroorganisme. Penelitian ini bertujuan menentukan dosis optimum kombinasi 70% pyrolyzed reject coal dan 30% pupuk kandang ayam terhadap sifat kimia tanah dan pertumbuhan padi di Kabupaten Karawang. Penelitian menggunakan Rancangan Petak Terbagi dengan petak utama RCP (70% reject coal + 30% pupuk kandang ayam) dan RCBP (70% pyrolyzed reject coal + 30% pupuk kandang ayam), serta dosis 0, 5, 10, 20 dan 40 t ha?¹ dengan tiga ulangan. Pyrolyzed reject coal diperoleh melalui proses pirolisis menggunakan reaktor pirolisis dengan suhu 350°C selama 90 menit. Berdasarkan hasil analisis kimia, tanah awal memiliki pH agak masam (5,60) dan KTK rendah (16,4). Hasil analisis tanah pascapanen menunjukkan perlakuan RCBP meningkatkan pH (5,73) dan C-organik (2,02%) dibandingkan RCP (pH 5,65; C-organik 1,87%). Dosis 40 t ha?¹ menghasilkan pH (6,05) dan C-organik (2,46%). Namun, tidak berbeda nyata dengan dosis 10 (pH 5,66; C-organik 1,93%) dan 20 t ha?¹ (pH 5,70; C-organik 2,07%). Logam berat total pada seluruh perlakuan tergolong rendah terhadap nilai baku yang digunakan, yaitu Pb hanya 1,52–1,85 ppm dan masih jauh di bawah Total Konsentrasi Tingkat C (TK-C) (300 ppm), Cd tidak terdeteksi atau <3 ppm, serta Ni 1,34–2,93 ppm dan masih <60 ppm sehingga secara umum tanah pascapanen belum menunjukkan risiko toksisitas Pb, Cd dan Ni. Perlakuan RCBP meningkatkan tinggi tanaman pada 5 MST (64,4 cm) dibandingkan RCP (63,3 cm), sedangkan pada 7 MST tidak berbeda nyata meskipun RCBP tetap lebih tinggi (86,4 cm dibandingkan 85,4 cm). Dosis 40 t ha?¹ menjadi perlakuan terbaik untuk tinggi tanaman karena berbeda nyata pada 5–7 MST dibandingkan kontrol, 5, 10 dan 20 t ha?¹. Pada jumlah anakan, RCBP menghasilkan nilai lebih tinggi (4,00 dan 31,0 anakan rumpun?¹) dibandingkan RCP (3,00 dan 30,0 anakan rumpun?¹), sedangkan dosis 40 t ha?¹ menghasilkan jumlah anakan tertinggi pada 5 MST (32,0) dan 7 MST (34,0 anakan rumpun?¹). RCBP meningkatkan parameter generatif dibandingkan RCP, yaitu gabah bernas 716 butir gabah rumpun-1 (RCBP) dan 565 butir gabah rumpun-1, gabah total 1.943 butir gabah rumpun-1 (RCBP) dan 1599 butir gabah rumpun-1 (RCP), bobot 1.000 bulir 29 g (RCBP) dan 26 g (RCP), gabah kering panen 6,35 t ha?¹ (RCBP) dan 5,62 t ha?¹ (RCP), gabah kering giling 5,44 t ha?¹ (RCBP) dan 4,63 t ha?¹ (RCP). Dosis 40 t ha?¹ berbeda nyata dibandingkan 0, 5 dan 10 t ha?¹, serta tidak berbeda nyata dengan 20 t ha?¹ pada parameter gabah kering panen. Pada parameter gabah kering giling, dosis 40 t ha?¹ berbeda nyata dibandingkan 0 dan 5 t ha?¹, tetapi tidak berbeda nyata dengan 10 dan 20 t ha?¹. Dosis 40 t ha?¹ juga berbeda nyata dibandingkan 0, 5 dan 10 t ha?¹, serta tidak berbeda nyata dibandingkan 20 t ha?¹ pada parameter gabah kering panen per hektar. Perbedaan nyata juga diamati pada parameter gabah kering giling per hektare. Peningkatan hasil tersebut menunjukkan bahwa semakin besar jumlah amelioran yang diberikan, semakin besar pula jumlah permukaan reaktif yang tersedia untuk mengontrol dinamika hara dalam tanah. Kandungan serapan logam berat tanaman tetap rendah, dengan Cd 0,02–0,025 ppm dan Cr 1,23–1,29 ppm. RCBP (1,24) menurunkan Cr dibandingkan RCP (1,29) karena pyrolyzed reject coal meningkatkan kemampuan adsorpsi logam. Pemberian dosis 40 t ha?¹ tidak berbeda nyata dengan 20 t ha?¹ pada seluruh parameter hasil. Hal tersebut menunjukkan bahwa dosis 20 t ha?¹ telah mampu memberikan respons yang setara dengan dosis 40 t ha?¹, sehingga dosis 20 t ha?¹ dapat direkomendasikan sebagai dosis optimum yang lebih efisien dalam meningkatkan produktivitas tanaman padi.

Rice is the staple food of the Indonesian people. Rice production in Indonesia and West Java declined by 2.93% and 8.5%, respectively, while Karawang Regency—a major rice-producing region—experienced a 6.67% drop in productivity due to a decline in soil quality and organic matter. The use of organic materials, such as chicken manure, has the potential to improve soil fertility and increase the efficiency of inorganic fertilizers. Coal waste in the form of coal reject has the potential to be used as a soil conditioner; however, its use as pyrolyzed coal reject in rice paddy soils remains limited. Pyrolyzed coal reject can improve soil porosity, nutrient retention, and the habitat for microorganisms. This study aims to determine the optimal application rate of a mixture consisting of 70% pyrolyzed coal reject and 30% chicken manure on soil chemical properties and rice growth in Karawang Regency. The study used a split-plot design with main plots of RCP (70% coal reject + 30% chicken manure) and RCBP (70% pyrolyzed coal reject + 30% chicken manure), as well as application rates of 0, 5, 10, 20, and 40 t ha?¹ with three replicates. Pyrolyzed coal reject was obtained through a pyrolysis process using a pyrolysis reactor at a temperature of 350°C for 90 minutes. Based on the results of chemical analysis, the initial soil had a slightly acidic pH (5.60) and low cation exchange capacity (CEC) (16.4). The results of post-harvest soil analysis showed that the RCBP treatment increased pH (5.73) and organic carbon (2.02%) compared to the RCP treatment (pH 5.65; organic carbon 1.87%). The 40 t ha?¹ application rate resulted in a pH of 6.05 and organic carbon of 2.46%. However, these values were not significantly different from those of the 10 t ha?¹ application rate (pH 5.66; organic carbon 1.93%) and the 20 t ha?¹ application rate (pH 5.70; organic carbon 2.07%). Total heavy metals in all treatments were classified as low relative to the reference values used: Pb was only 1.52–1.85 ppm and remained well below the Total Concentration Level C (TK-C) (300 ppm); Cd was not detected or was <3 ppm; and Ni was 1.34–2.93 ppm and remained <60 ppm. Thus, in general, the post-harvest soil does not yet pose a risk of toxicity from Pb, Cd, and Ni. The RCBP treatment increased plant height at 5 MST (64.4 cm) compared to the RCP treatment (63.3 cm), whereas at 7 MST there was no significant difference, although the RCBP treatment remained taller (86.4 cm compared to 85.4 cm). The 40 t ha?¹ rate was the best treatment for plant height because it differed significantly at 5–7 MST compared to the control and the 5, 10, and 20 t ha?¹ rates. In terms of the number of tillers, RCBP produced higher values (4.00 and 31.0 tillers per clump) compared to RCP (3.00 and 30.0 tillers per clump), while the 40 t ha?¹ application rate produced the highest number of tillers at 5 MST (32.0) and 7 MST (34.0 tillers per clump). RCBP showed improved yield parameters compared to RCP, namely 716 grains of mature paddy per clump (RCBP) and 565 grains of mature paddy per clump, a total of 1,943 grains of paddy per clump (RCBP) and 1,599 grains per hill (RCP), 1,000-grain weight of 29 g (RCBP) and 26 g (RCP), dry harvested grain yield of 6.35 t ha?¹ (RCBP) and 5.62 t ha?¹ (RCP), and milled dry grain yield of 5.44 t ha?¹ (RCBP) and 4.63 t ha?¹ (RCP). The 40 t ha?¹ treatment differed significantly from the 0, 5, and 10 t ha?¹ treatments, but did not differ significantly from the 20 t ha?¹ treatment in terms of dry harvested grain yield. In terms of dry milled grain yield, the 40 t ha?¹ treatment differed significantly from the 0 and 5 t ha?¹ treatments, but did not differ significantly from the 10 and 20 t ha?¹ treatments. The 40 t ha?¹ treatment also differed significantly from the 0, 5, and 10 t ha?¹ treatments but did not differ significantly from the 20 t ha?¹ treatment in terms of dry harvested grain yield per hectare. Significant differences were also observed in terms of dry milled grain yield per hectare. This increase in yield indicates that the greater the amount of soil amendment applied, the greater the reactive surface area available to control nutrient dynamics in the soil. Heavy metal uptake by the plants remained low, with Cd at 0.02–0.025 ppm and Cr at 1.23–1.29 ppm. RCBP (1.24) reduced Cr levels compared to RCP (1.29) because pyrolyzed coal reject enhances metal adsorption capacity. The application of 40 t ha?¹ did not differ significantly from that of 20 t ha?¹ for all yield parameters. This indicates that the 20 t ha?¹ application rate was able to produce a response equivalent to that of the 40 t ha?¹ application rate; therefore, the 20 t ha?¹ application rate can be recommended as the optimal rate that is more efficient in increasing rice productivity.