Physical Characteristics of Ultisols and the Impact on Soil Loss During Soybean (Glycine Max Merr) Cultivation in Wet Tropical Area

Physical characteristicsare among soil propertiesaffecting the susceptibility to erosion. Determination of physical characteristics of Ultisol was aimed to evaluate the dynamics of soil properties as well asthe impact on soil erosion and runoff (RO) during soybean cultivation in wet tropical area. Soybean was planted within erosion plots (18 m2) at 25% slope in UltisolLimauManis (having > 5000 mm annual rainfall). Soil samples for physical properties (soil texture, bulk density, total pore, permeability, aggregate stability,and organic carbon) as well as amount of RO and soil loss were analyzed at 5 different times (stages) during the cultivation. The results showed that there was fluctuation in physical properties of Ultisol during the cultivation. Likewise, the amount of runoff and soil loss also changed during the study. Among the physical properties analyzed, the aggregate stability index of the soil highly correlated to the amount of RO (R2=0.73) and soil loss (R2=0.94). Amount of RO and soil loss was controlled by soybean development at the average rainfall intensity ≤ 36 mm/day, but not at rainfall intensity >36 mm/day. It is suggested not to open heavily clayey-low OC soils for seasonal crop farming during rainy season in wet tropical area

Pengaruh Pemberian Amelioran terhadap Laju Infiltrasi pada Tanah Psamment dan Pertumbuhan Serta Hasil Tanaman Jagung (Zea Mays)

Penelitian ini bertujuan untuk mengetahui pengaruh pemberian ameliorant terhadap laju infiltrasi tanah serta pertumbuhan dan hasil tanaman jagung (Zea mays) pada Psamment. Penelitian ini dilaksanakan di Nagari Katapiang, Kecamatan Batang Anai Padang Pariaman, dan analisis tanah di laboratorium Jurusan Tanah Fakultas Pertanian Universitas Andalas. Penelitian ini dilaksanakan pada bulan April hingga Oktober 2018 menggunakan Rancangan Acak Kelompok (RAK) dengan 8 perlakuan dan 4 ulangan. Data yang diperoleh dianalisis dengan statistik dan dilanjutkan dengan uji DNMRT taraf 5% untuk nilai F yang berbeda nyata. Perlakuan yang diberikan adalah A = Kontrol, B = Mulsa jerami padi (10 ton/ha), C= Biochar sekam padi (20 ton/ha), D = liat (20 ton/ha), E = Mulsa jerami padi (10 ton/ha) + liat (20 ton/ha), F =Mulsa jerami padi (10 ton/ha) + Biochar sekam padi (20 ton/ha), G = Biochar sekam padi (20 ton/ha) +liat (20 ton/ha), H = Mulsa jerami padi (10 ton/ha) + Biochar sekam padi (20 ton/ha) +liat (20 ton/ha). Hasil penelitian menunjukkan bahwa penambahan perlakuan kombinasi biochar sekam padi, tanah liat, dan mulsa jerami padi terdapat peningkatan tertinggi terhadap nilai TRP yaitu sebesar 23,23%, kandungan bahan organik sebesar 2,78%, dan kadar air tanah sebesar 6%, dan penurunan nilai BV sebesar 0,47 g/cm3. Penurunan nilai laju infiltrasi tertinggi berada pada perlakuan kombinasi mulsa jerami padi, liat dan biochar sekam padi dengan nilai sebesar 506,6 mm/jam dibandingkan kontrol sebesar 994,7 mm/jam, namun masih dalam kriteria yang sama. Penambahan pelakuan kombinasi mulsa jerami padi, liat dan biochar sekam padi pada Psamment dapat meningkatkan hasil tanaman jagung sebesar 11,05 kg/plot jika dibandingkan dengan kontrol sebesar 6,72 kg/plot

Nitrogen Balance in Forage Rice (Oryza sativa L. cv. Tachisuzuka) Cultivation in Pots with Animal Manure Application

Experiments were conducted to evaluate the nitrogen (N) balance in forage rice cultivation using animal manure in 1/2,000a Wagner pots in a greenhouse. The cattle manure and poultry manure were applied at 3 levels of N (0, 14, 28 g available N m–2) without additional chemical fertilizer application. The pots were designed to simulate the fluid percolation in the paddy field. The results indicated increasing levels of N input improved plant height, tiller number, SPAD value and biomass (straw, grain and root) production, however, N leaching from soil (Andosols) due to percolating water also increased. The planting of rice plants proved to reduce 30% of the N leaching loss. N use efficiency, the ratio of N uptake by plant per unit N application, decreased in higher N application. The N uptake by the above-ground parts occupied about 66% of the whole plants