Production capacity and its WUE of different crops in Lishu county of Jilin Province

Northeast China is an important grain production area of China. The maize planting is increasing recently. In this study, we explored the production capacity of the other crops in order to provide valuable information for laying out more reasonable and effective planting structure in the Northeast China. 2-year experiments were conducted in Lishu county of Jilin Province in 2016 and 2017. Crop treatments by water treatments were designed. Crops included soybean, wheat, millet and potato and 2 water treatments included irrigation and rain-fed method. The crops were planted in traditional way. The crop yield and soil water content were measured. The water consumption was calculated based on water balance equation. The water deficit rate was defined as the percentage of difference of precipitation and water requirement and water consumption. Water requirement was calculated based on potential evapotranspiration of FAO formula and crop coefficient. The water use efficiency was calculated based precipitation, irrigation and their sum. Then the yield and water use efficiency were converted into energy in order to compare different crops. Economic benefit of these 4 crops under different water treatments were compared. The results showed that compared to historical average, the year of 2016 was wet year and the year of 2017 was normal year. In the wet year, the precipitation was rich during the early and middle stages of crops while it was scarce during the early and late stages of the crops. The crop water requirements were higher than or equaled to in the wet year than in normal year. The wheat-buckwheat had the highest crop water consumption in 2016 while the potato had the lowest water consumption. During the initial stage, most of the crops had surplus precipitation. By the middle stage, most of them started to show shortage of precipitation. For the whole growth period, the water deficit of potato was the highest and that of the millet was the lowest. The potato had higher production capacity (over 100 000 GJ/hm2 under rain-fed treatment) than the other crops. The production capacity of the other crops was not significantly different (P>0.05). Irrigation could only improve production capacity of potato. However, the impact of irrigation on potato production capacity was different in different precipitation patterns. In normal year, the increase of production capacity of potato was much higher than the wet year. In addition, the water use efficiency of production capacity of potato was higher than the others. The irrigation water use efficiency of potato could be more than 20 GJ/mm, far higher than the other crops. Thus, the economic benefit of water use based on production capacity of potato was also the highest. Compared to the soybean and wheat-buckwheat, the millet was higher in the economic benefit of water use based on production capacity in wet year. Therefore, potato and millet had greater advantages than soybean and spring wheat in planting structure adjustment based on crop production capacity, the precipitation use efficiency in production capacity, irrigation water use efficiency in production capacity, agricultural water use efficiency in production capacity and economic coefficient in Lishu county of Jilin province.