Suitable evaluation for crops and water-saving irrigation methods for arable sandy land in Inner Mongolia

Abstract: As the ecological security barrier in the north of China, Inner Mongolia is also the important agricultural and animal husbandry production base, and about one third of this region belongs to sandy land. Some sandy land is arable since plant growth requirements can be satisfied under natural conditions or when some artificial measures are used. Usually, some problems such as water shortage, water and nutrition leakage, high temperature on soil surface, and complex topography, exist for arable sandy land, but farmers cannot take effective measures to deal with these problems except make some simple management according to their experiences. The difficulties in optimizing crop planting structure and choosing irrigation methods usually lead to substantial waste of water and nutrient resources, lowing land productivity level, and even un-cultivation land. In order to provide references for local farmers to sustainably use arable sandy land by overcoming these limitation factors, seven farm crops (spring maize (Zea mays), spring wheat (Triticum aestivum), millet (Pennisetum glaucum), soybean (Glycine max), rapeseed (Brassica rapus), rice (Oryza sativa) and potato (Solanum tuberosum)), which had large planting areas and higher grain yields in the last five years in Inner Mongolia, were evaluated according to their water requirement, effective accumulated temperature, soil pH value, response to increased temperature, economic benefit, and drought resistance, respectively. Meanwhile, eight forage grasses (Agropyron, Artemisia desertorum, Caragana korshinskii Kom, Elymus dahuricus Turcz, Leymus chinensis Tzvel.cv, Medicago sativa L, Astragalus adsurgens Pall., and Bromus inermis Leyss.cv.) with large planting areas in the last 10 years and one another popular forage grass (Zea mays L.cv.) in Inner Mongolia were also evaluated according to precipitation, temperature, soil pH value, nutrient value, respectively. Based on crop planting models, the specific characteristics of various irrigation methods, as well as specific soil and climate conditions and topography characteristics for arable sandy land in Inner Mongolia, appropriate water saving irrigation method was chosen for each crop. The results indicated that the rank of comprehensive suitability for farm crops in arable sandy land was: spring maize, spring wheat, millet, soybean, rape seed, rice and potato. For forage grass, the rank of comprehensive suitability in arable sandy land was: Agropyron, Artemisia desertorum, Zea mays L.cv., Caragana korshinskii Kom, Elymus dahuricus Turcz, Leymus chinensis, Medicago sativa L., Astragalus adsurgens Pall. and Bromus inermis Leyss.cv. These loosely planted (wide seeding/row spacing) crops such as maize, rice, soybean and potato were suggested to be drip-irrigated and even under mulch film, while those closely planted (narrow seeding/row spacing) crops such as forage grass were suggested to be irrigated through sprinklers. When crop suitability was evaluated, we used data from various published papers with different experimental conditions. In addition, when evaluating indicators were chosen and their weight factors were determined, subjectivity might really exist. Therefore, the evaluating method adopted in this study can be further improved. However, the results are still reliable and valuable for application and can provide reference for utilizing arable sandy land in Inner Mongolia sustainably and efficiently.