The concern about global climate change continues to increase research interest regarding carbon and nitrogen dynamics in the soil. This is based on their role in maintaining soil fertility, which can instead be a source of greenhouse gas emissions if not managed properly, while threatening food security. Humid tropical conditions enable intensive agricultural cultivation with various cropping systems to fulfill the demand for agriculture products. Such climate accelerates the soil organic matter decomposition rate so that it strongly influences soil carbon and nitrogen dynamics. However, inappropriate implementation of intensive agricultural systems that does not consider the balance between carbon and nitrogen input and output, negatively affects soil fertility, mainly decreasing soil organic carbon and total soil nitrogen, changing the composition of carbon and nitrogen owing to the loss of soil organic matter through erosion and leaching, thus, causing soil degradation. Mitigation strategies can be performed by using organic matter and crop residue, crop rotation and improvement of crop pattern, soil tillage and fertilization, cover crops and mulch. Sustainable land management for maintenance of soil organic carbon and total soil nitrogen dynamics should be locally and globally developed and adopted for a more sustainable agricultural system. Recovery of soil capacity to accumulate carbon is a strategic step to reduce the impact of climate change. Hence, an intensive study on efficient soil organic carbon management is required to improve food production and mitigation of climate change to attain sustainable development goals in 2030.

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Green manure application helps maintain soil fertility, reduce chemical fertilizer use, and carbon sequestration in the soil. Nevertheless, the application of organic matter in paddy fields induces CH₄ and N₂O emissions. Prolonging mid-season drainage reduces CH₄ emissions in paddy fields. Therefore, the combined effects of green manure application and mid-season drainage prolongation on net greenhouse gas emission (NGHGE) were investigated. Four experimental treatments were set up over a 2-year period: conventional mid-season drainage with (CMG) and without (CM) green manure and prolonged (4 or 7 days) mid-season drainage with (PMG) and without (PM) green manure. Astragalus sinicus L. seeds were sown in autumn and incorporated before rice cultivation. No significant difference in annual CH₄ and N₂O emissions, heterotrophic respiration, and NGHGE between treatments were observed, indicating that green manure application and mid-season drainage prolongation did not influence NGHGE. CH₄ flux decreased drastically in PM and PMG during mid-season drainage under the hot and dry weather conditions. However, increasing applied carbon increases NGHGE because of increased CH₄ and Rh. Consequently, combination practice of mid-season drainage prolongation and green manure utilization can be acceptable without changing NGHGE while maintaining grain yield in rice paddy fields under organically managed rice paddy fields.

Physiological Responses of Oil Palm Seedlings to the Drought Stress Using Boron and Silicon Applications

Climate change had changed the rainfall patterns and causing tomato plants to suffer from drought in a certain period. It affects the morphology and physiology characters of the plant, and thus these characters can be used as indicators to predict plant tolerance to drought. The study aimed to determine the relationship between several physiological characters with tomato yield under drought stress. The study was conducted using 7 lowland tomato cultivars, namely 'Zamrud', 'Permata F1', 'Mirah', 'Tombatu F1', 'Tyrana F1', 'Ratna' and 'Tymoti F1'. Drought was appliedby 8 days interval of watering. Relative water content, membrane stability index, chlorophyll, and proline content were measured when the plant entered the maximum vegetative of growth stage. The results showed a high correlation (r > 0.6) between membrane stability index with fruit weight per plant; while the proline, chlorophyll and relative water contents resulted in low correlation (r < 0.5) with fruit weight. The membrane stability index was better in indicating the drought tolerance in tomato than other physiological characters