内蒙古宜耕沙地作物适宜性评价与节水灌溉方式配置

内蒙古自治区拥有大量宜耕沙地,但普遍都面临干旱缺水、土壤漏水漏肥、地表高温、微地形复杂等问题,经营管理不善不仅会进一步加剧水资源危机,而且还会因土地生产力水平低下而导致土地撂荒与沙化。为了在作物种植结构优化与灌溉方式选配方面给当地农户提供参考依据,该研究从内蒙古宜耕沙地可持续利用过程中所遇到的共性问题出发,以内蒙古自治区近5 a产量和种植面积都居前的7种农作物(春玉米、春小麦、谷子、大豆、油菜、水稻、马铃薯)为评价对象,从需水量、有效积温、土壤pH值、增温响应、经济效益、耐旱性能等6方面对其适宜性进行分析与比较。同时,又以该地区近10 a种植面积居前的8种牧草(冰草属牧草、沙蒿、柠条锦鸡儿、批碱草属牧草、羊草、紫花苜蓿、沙打旺、无芒雀麦)和1种近年来得到广泛关注的牧草(青贮玉米)为评价对象,从降水量、气温、土壤pH值、营养价值等四方面对其适宜性进行了分析与比较。然后,针对各种作物的种植模式,结合各种灌溉方式的自身特点以及内蒙古宜耕沙地主要的土壤、气候、地形地貌特征,以提高水分与养分利用效率为主要目标,为各种作物选配了适宜的节水灌溉方式。结果表明适宜在内蒙古宜耕沙地上种植的农作物依次为春玉米、春小麦、谷子、大豆、油菜、水稻、马铃薯,牧草依次为冰草属牧草、沙蒿、青贮玉米、柠条锦鸡儿、批碱草属牧草、羊草、紫花苜蓿/沙打旺、无芒雀麦。在条件许可的情况下建议玉米、水稻、大豆、马铃薯等疏植作物选用滴灌甚至膜下滴灌,其他密植作物(包括牧草)选用喷灌。因该研究在对作物适宜性进行评价时所采纳的数据均来自于公开发表的文献资料,试验条件存在较大差异,并且所采纳的评价指标以及权重因子在一定程度上仍存在主观性,导致评价方法仍有待进一步改进与完善,但相关结果仍可为内蒙古宜耕沙地可持续高效利用提供借鉴。

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.