The problem of rice farming in Indonesia is the increasing extent of nutrient-poor land due to the lack of addition of organic matter and continuously inundated irrigated rice fields, causing the production of greenhouse gas emissions, such as methane gas (CH₄), to increase. The study aims to determine the impact of organic fertilizers and rice varieties on rice yield, methane emissions, and the feasibility of farming in nutrient-poor rice fields. The study used a randomized block design in factorial with four replicates. The first factor is the type of organic fertilizers (compost of rice straw and goat manure), and the second factor is the variety of rice (Ciherang, Inpari 20, and Inpari 30). The results showed that the productivity of Inpari 20 (8.02 t·ha⁻¹) was significantly higher than that of Inpari 30 (6.10 t·ha⁻¹) and Ciherang (6.91 t·ha⁻¹). The highest yields of Harvest Dry Grain (HDG) to Milled Dry Grain (MDG) were the Inpari 20 (88.23%), Inpari 30 (86.94%), and Ciherang (85.04%). Methane (CH₄) emissions were highest in the Ciherang variety (56.4 kg h⁻¹ season⁻¹), followed by Inpari 30 (40.8 kg h⁻¹ season⁻¹), and lowest in Inpari 20 (22.3 kg h⁻¹ season⁻¹). Compared to Inpari 30 and Ciherang varieties, the Inpari 20 variety with rice straw compost has broad development viability in nutrient-poor paddy fields (highest R/C ratio and break-even point). More research on organic rice is needed to determine the productivity and emissions (methane, nitrite, carbon dioxide).

The serious problems of sandy soils for crop development are low water-holding capacity, nutrient retention, and low content of all nutrients. The objective of the study was to increase the nutrient content of sandy soil and evaluate nutrient types that mostly affect the high shallot yield with reasonable economic values. The field experiment was conducted on the upland sandy loam soil. Six treatments consisting of complete nutrients, N-, P-, K-, Mg- and S-omission tests were arranged in a randomly completed block design with four replicates. The observed parameters included soil physicochemical properties, tissue nutrient content, growth, yield, and input-output of shallot cultivation. The results showed that N, P, K, Mg and S application successfully increased shallot bulb, achieving 11.43 t ha⁻¹ on sandy soil. The order of shallot tissue content was K > N > P~Mg > S, where the S, P, N, and Mg are limiting factors, as revealed by significantly lower relative yield (varying from 79 to 88%). The highest weight loss during storage occurred for S-omission treatment (40 to 60%), indicating insufficient S tissue is the most responsible for the quality of shallot. The complete nutrient treatment gave the highest income (7446.09 USD ha⁻¹) with a revenue cost ratio of 2.41 compared to other treatments. The tolerance limit for price reductions that do not cause losses was 58.59%.

Rice production in the karst dryland is still low, due to soil characteristics that lack nutrient availability. Meanwhile, upland rice has received less attention, and it has not been used to its full potential. This study aimed to evaluate the effect of various combinations of inorganic fertilizers, poultry manure, and upland rice varieties on the production and economic value of karst dryland in Gunungkidul, Yogyakarta. This experiment was arranged in a factorial design, with inorganic fertilizers, poultry manure, and upland rice varieties set in a randomized block design with three replications. The first factor was a combination of inorganic and organic fertilizer rates: 72 N kg ha⁻¹ + 26 P₂O₅ kg ha⁻¹ + 25 K₂O ha⁻¹ + 3 t ha⁻¹ organic, 92 N kg ha⁻¹ + 36 P₂O₅ kg ha⁻¹ + 30 K₂O kg ha⁻¹ + 2 t ha⁻¹ organic, 112 N kg ha⁻¹ + 46 P₂O₅ kg ha⁻¹ + 35 K₂O kg ha⁻¹ + 1 t ha⁻¹ organic. The second factor is the upland varieties of Inpago 8, Inpago 10, and Inpago 12 and lowland variety Inpari 42 Agritan GSR, as checked. Based on the study, we concluded that the combination of 92 N kg ha⁻¹ + 36 P₂O₅ kg ha⁻¹ + 30 K₂O kg ha⁻¹ + 2 t ha⁻¹ poultry manure fertilizers with Inpago 8 resulted in an IDR profit of 23,586,000 ha⁻¹, and it is the most recommendable fertilizer and variety combination to be developed in the karst dryland, in consideration of land fertility and sustainability.