不同生产目标条件的马铃薯水氮管理优化

基于不同生产目标，优化不同降水年型下的水氮耦合方案对马铃薯生产的可持续发展具有重要意义。该研究基于中国北方农牧交错带地区27个站点的气象数据、土壤数据和管理数据驱动APSIM-Potato模型，设置不同的灌溉和氮肥耦合情景，基于土壤水分亏缺量设置灌溉情景（共设置10个灌溉梯度，即土壤水分亏缺范围为10～100 mm，间隔10 mm），施氮肥量为30～210 kg/hm2，梯度为30 kg/hm2，模拟分析不同降水年型下水氮耦合对马铃薯产量、水分利用效率和经济收益的影响，并推荐不同降水年型下获得不同生产目标的最佳水氮耦合方案。结果表明：农牧交错带干旱年型、正常年型和湿润年型下不同水氮耦合方案的马铃薯最高产量分别为30 200～39 400、28 900～38 800和27 000～38 000 kg/hm2，其中干旱年型下产量最高。干旱年型、正常年型和湿润年型下获得最高产量的灌溉量分别为589、544和512 mm，氮肥投入量均为最大值，即210 kg/hm2。干旱年型、正常年型和湿润年型下不同水氮耦合方案的马铃薯最高水分利用效率分别为85.9、90.2和92.2 kg/(mm·hm2)，获得最高水分利用效率的灌溉量分别为172、107和87 mm，氮肥投入量均在60～120 kg/hm2之间，其中干旱年型下投入量为60 kg/hm2的站点比例最高。干旱年型、正常年型和湿润年型不同水氮耦合方案下马铃薯的最高收益分别为19 340、18 610和18 470元/hm2，获得最高收益的灌溉量分别为226、152和116 mm，干旱年型和正常年型获得最高收益的氮肥投入量均在30～90 kg/hm2之间，湿润年型下获得最高收益的氮肥投入量在60～90 kg/hm2之间。研究结果有助于当地生产者基于不同的生产目标制定较优的水氮管理方案。

Optimizing irrigation and nitrogen management for potato production under multi-objective production conditions

Abstract: Water is a determining factor in crop production, particularly with the increase of irrigation areas and crops in recent years. Water shortage has posed a great challenge to crop production in North China. Fortunately, the nitrogen (N) fertilizer can serve as another key factor for crop growth and yield formation. However, there is a severe unbalance between the supply of N fertilizer and crop demand. It is also a trade-off between the irrigation and N fertilizer in most parts of Agro-Pastoral Ecotone (APE), which is one of the staple production regions for potatoes in China. Therefore, it is necessary to optimize the irrigation and N management for potato sustainable production using various production goals under different precipitation years. In this study, 27 study sites in the APE were selected to explore the coupling impacts of irrigation and N on the potato yield, Water Use Efficiency (WUE), and economic benefits using the Agricultural Production Systems Simulator (APSIM) Potato model. A two-year field experiment was also carried out under different treatments of irrigation and N fertilizer at a typical site in the APE. Specifically, ten irrigation levels were set in the test, where the deficit values ranged from 10 to 100 mm with the interval of 10 mm, while the application amount of N fertilizer ranged from 30 to 210 kg/hm2 with the interval of 30 kg/hm2. Three types of precipitation years (dry, normal, and wet) were divided in the APE, according to the guarantee rate of precipitation. Subsequently, the WUE was calculated using the ratio of fresh potato yield to evapotranspiration. The economic benefit was the difference between the gross income and the total inputs, where the gross income was the product of the total fresh yield and unit price. Among them, the inputs included the cost of seeding, irrigation, fertilization, use of fungicides and pesticides, tillage, planting and harvesting, and labor. The results showed that the APSIM-Potato model performed well to simulate the phenology, the soil water content of 1m depth, potato N uptake, and yield. The yield of rainfed potato without the application of N fertilizer was ranged from 4 760 to 18 500 kg/hm2, from 9 200 to 20 900 kg/hm2, and from 11 900 to 21 500 kg/hm2 under dry, normal and wet precipitation years, respectively. More importantly, the yields were the lowest in the middle APE under all types of precipitation years. The maximum yield of potato was achieved under the dry year using different combinations of irrigation and N fertilizer. In addition, an optimal combination was achieved to maximize the yield, where the irrigation inputs were 589, 544, and 512 mm in dry, normal, and wet years, respectively, while the N application amounts were all 210 kg/hm2. The irrigation inputs were much higher in the eastern and western APE under all precipitation year types. The maximum WUEs were 85.9, 90.2, and 92.2 kg/ (mm·hm2) in the dry, normal, and wet years, respectively. An optimal combination was also achieved to maximize the WUE, where the irrigation inputs were 172, 107, and 87 mm in the dry, normal, and wet years, respectively, while the amounts of N were 60-120 kg/hm2. Among them, the proportion of sites with 60 kg/hm2 was the highest in the dry years. As such, the maximum economic benefits were 19 340, 18 610, and 18 470 Yuan/hm2 in dry, normal, and wet years, respectively. An optimal combination was also achieved to maximize the income, where the irrigation inputs were 226, 152, and 116 mm in dry, normal, and wet years, respectively, while the application amounts of N were 30-90 kg/hm2 in different year types. The proportion of sites with 90 kg/hm2 was the highest in the wet years. The finding can greatly contribute to formulating optimal management of irrigation and N fertilizer, according to various goals of potato production under different precipitation years.