The problems of soybean cultivation on tidal land are low in soil fertility, aluminum (Al) toxicity and poor availability of macro nutrients. Soil acidity and Al toxicity are often fixed by liming. The research aimed to determine the calculation method of lime requirement and its application method for soybean on tidal land. The research was conducted on tidal land in South Kalimantan, Indonesia. Treatment consisted of two factors and arranged in randomize complete block design, replicated three times. The first factor was the method of lime rate calculation: (1) no liming, (2) liming based on 10% of Al saturation, (3) liming based on 20% of Al saturation, (4) liming based on 30% of Al saturation, (5) liming based on 0.5 x exchangeable Al, and (6) liming based on 1 x exchangeable Al. The second factor was the method of application: (1) surface and (2) mixed within 20 cm soil depth. The results showed that liming by mixing dolomite with soil within 20 cm depth resulted in 8% higher plant height compared to that applied on the soil surface. The highest yield was obtained when liming at rate equivalent to 10% of Al saturation was mixed with soil within 20 cm depth.

Groundnut cultivation on saline soil facing complex problems associated with high electrical conductivity (EC), toxic effects of Na cation, imbalance nutrients, and N and P deficiency. Objective of this research was to determine optimum rate of N and P fertilizers for groundnut on saline soil. The trial was conducted on saline soil in Lamongan (EC 8-15 dS/m, pH>8.0, low N, high P) and Tuban (EC 8-16 dS/m, pH>8.0, low N and P) during dry season year 2017. Treatment consisted of two factors, and the combinations were arranged in a completely randomized block design with three replications. The first factor was four N fertilizer rates (0, 23, 46, and 69 kg N/ha), and the second factor was four P fertilizer rates (0, 36, 72, and 108 kg P 2 O 5 /ha). Results showed that nitrogen fertilization had no effect on plant height, number of filled pod and plant stand, but improved chlorophyll content, increased100 seed weight, harvest index and yield. Phosphorus fertilization had no effect on all parameters observed, except on 100 seed weight and plant stand. The yield response to N fertilization was linear and quadratic, depending on the location. The optimum N rates was 62-69 kg N/ha. The results indicated that N fertilization had more important role than P fertilization for increasing groundnut yield on saline soil, although the growth did not improve.

Productivity of agricultural land in coastal area is limited by salinity. Planting tolerant variety combined with amelioration is an effective management to increase productivity of salt affected land. The objective of this study was to identify effective ameliorant for improving growth and yield of groundnut on saline soil. The trial was conducted on saline soil in Tuban from May to September 2015. The trial consisted of two factors that were arranged in a completely randomized block design, three replications. The first factor was two groundnut varieties (Domba and Hypoma 1). The second factor was six soil ameliorations (control, 120 kg/ha K2O, 2.5 t/ha dolomite, 2,5 t/ha of gypsum, 2.5 t/ha of manure, and 1.5 t/ha of gypsum + 2.5 t/ha of manure). Results showed that Domba and Hypoma 1 varieties could tolerate and completed their life cycle at insitu saline condition. Hypoma 1 was more prospective to be developed in saline condition associated with higher survival as well as better pod setting and seed development than Domba. Combination of gypsum and manure provided better effect than other treatments in improving saline soil, since it reduced exchangeable Na, Na saturation, and EC of soil, and also improved groundnut yield.

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KEYWORDSOrganic matter quality Soil fertility N mineralization N uptake T ypic Hapludults ABSTRAC TFertility of soil and crop biomass production are directly affected by organic matters present in soil. T he availability of organic matter and its quality plays a key role in the soil, plants and environment sustainability. Present study was aimed to investigate the influence of organic matter and soil fertility on nitrogen mineralization and its uptake by cassava. T o estimate the parameters of N mineralization potential (N0), rate of mineralization (k), and activation energy (Ea) incubation experiments were conducted in the laboratory, using a first order equation. While the relationship between the parameters of N mineralization and nutrient uptake were carried o ut in green house pot experiment s. Value of N0, k and Ea were reported 400 -1156 mg/kg, 0.0056 -0.098 per week and 10166 -31478 J mol -1 respectively. N mineralization was positively correlat ed with water soluble N, N-Particulate Organic Matter, N microbial biomass, C-Particulate Organic Matter, C microbial biomass, N-total plant dry weight, N concentration and N uptake of cassava plants, however it was negatively correlated with C:N ratio. A higher N mineralization rate was found in soils with low C:N ratio of organic matter and higher fertility, as indicated by the value of N0, k and N0.k, which were higher than that of high C:N ratio of organic matter and low fertility of soil.