Rice production and food security in Asian Mega deltas—A review on characteristics,vulnerabilities and agricultural adaptation options to cope with climate change

Asian Mega deltas (AMDs) are among the world´s most important rice-growing areas and vital for food security. This review describes the major environmental and agricultural characteristics as well as current and future threats to food production and livelihood, using three AMDs as examples, namely the Ganges–Brahmaputra delta in Bangladesh, the Ayeyarwady delta in Myanmar and the Mekong River delta in Vietnam. In addition, we analysed the most widely used agricultural adaptation methods in these areas. The major threat to agriculture is salinity intrusion and water scarcity, which consequently leads to a shortage of irrigation water and yield reduction. The most common applied agricultural adaptation strategies are the use of salt-tolerant varieties and the adjustment of cropping calendars, as well as the use of water-saving technologies. It was found that there are many concepts that address individual problems, but a comprehensive and integrated concept for delta regions to adapt to climate change is still missing.     

Pattern of non-commercial energy consumption and availability in the Indian domestic sector— A case study

Non-commercial energy resources occupy a key position in rural areas of India. A survey was carried out to find the consumption pattern of non-commercial energy resources in the domestic sector of an Indian village. Dung cakes, Saccharum munja Roxb (a wild member of the grass family) and firewood were found to be the three main resources for cooking, smoking and heating. On the basis of quantities available, per capita amounts of energy resources and energy used were calculated. Dung cakes contributed more than 60% of the total cooking energy needs. A significant amount of dung cakes were burnt for tobacco smoking in a traditional device. After making dung cakes the rest of the dung was composted. S. munja formed a second source of energy. Surprisingly, firewood occupied the last position. Thus the first priority of using dung is to burn it for energy needs. This leads to less availability of dung for compost and is detrimental since negligible amounts of chemical fertilizer are used in agriculture. To use the dung optimally, for energy as well as for fertilizer, biogas technology may be introduced, but it has to be integrated after considering all the other aspects in toto. Also the widely different energy consumption pattern in this village compared to the national average highlights the importance of a micro-level study in planning.     

Impacts of long-term jujube tree/winter wheat–summer maize intercropping on soil fertility and economic efficiency—A case study in the lower North China Plain

Agroforesry is a common traditional practice in China, especially in the saline-alkaline regions, like the lower North China Plain (LNCP) characterized by lower yields of food crops. Adding trees to the agricultural land creates additional fruitsets or woody biomass besides food crops, enabling farmers to diversify the provision of farm commodities. However, the productivity of many agroforestry systems has been lower than expected in recent years, highlighting the need for a mechanistic understanding of below- or above-ground interactions. The study combined investigation and experimental data together to evaluate the effects of long-term intercropping agroforestry system [jujube tree (Zizyphus jujuba Mill. var. inermis (Bunge) Rehd.)/winter wheat–summer maize] on soil fertility balance, crop production and system economic efficiency over the past 22 years in LNCP, with a view to developing an effective fertilization management for the moderately alkaline soils. Except remain higher pH, the soils are basically free of sodic and soil salinity is not the major restriction factor for intercrops, even through there are some fluctuation with season and distance from jujube tree. The intercropping system significantly reduced soil nutrient contents, like soil organic C (SOC), total N (TN), available P (avail. P) and K (avail. K) in most parts of the ecotone of the system, but increased those nutrients in the belt of underneath the edge of tree canopy, The growth of intercrops at the belt of 3.5 m from tree was severely negative stressed by jujube tree in term of lower soil moisture, nitrate, avail. P and K although receiving more photosynthetically active radiation (PAR), whereas the winter wheat growing at the 2.5 m row had more water and nutrients supplied and thus produced more grain yield. Uneven fertilization to the ecotone (about 1–2.5 m of the intercrop field boundary) could partly offset the consumption and competition for nutrients between the tree and the intercrops, and improved the grain yields by 12.1% and 14.5% in the ecotone regions (distance from jujube trees) of 1.5 m for winter wheat and 2.5 m for summer maize by increasing respective yield components. Although the mean grain yield of intercropped winter wheat and summer maize was reduced by 35.6 and 35.2%, respectively, compared to sole cropping system, the intercropping system proved to be a profitable land use type based on net income and economic returns, in addition to the wood and ecological benefits of the jujube tree in the moderate desalinate- alkaline regions.