The technique of measuring soil moisture and supplementary irrigation makes wheat high-yield and water-saving

China Science and Technology Network (Reporter Wei Dong correspondent Yang Yu) although the wheat harvest is over, the villagers in Meihua Town, Gaocheng District, Shijiazhuang City, Hebei Province are still obsessed with the technology of measuring soil moisture and supplementary irrigation of wheat. Under the condition that the average amount of water used for irrigation per mu is only 67.6m3, which is 37.7mu less than that of the traditional irrigation method, the yield per mu still reaches 601.2 kg. We will continue to use this technology to achieve high yield next year. According to reports, this water-saving and high-yield technology was founded by a team led by Yu Zhenwen, academician of the Chinese Academy of Engineering and Professor of Shandong Agricultural University, and has been listed by the Ministry of Agriculture as the main agricultural technology in 2016.

In the view of Academician Yu Zhenwen, in the past production was accustomed to flood irrigation, regardless of soil moisture. This not only causes a waste of water resources, but also is not conducive to the growth of wheat. In order to study the water-saving and high-yield technology, it is necessary to find out which critical periods of wheat growth need watering and the best irrigation amount.

Huang-Huai-Hai region is the main wheat producing area in China, and the contradiction between supply and demand of water resources is prominent. For example, the average annual precipitation in Hebei Province is about 500 mm, and 60% to 70% are concentrated in June, July and August after the wheat harvest, and the precipitation during the wheat growing period can only meet 25% of its needs. The irrigated area of Huang-Huai-Hai wheat area accounts for 42% of the country's total, while agricultural irrigation accounts for 70% of the total water used for production and domestic use. Low water use efficiency and serious waste is a prominent problem in agricultural production in China.

The innovation team led by Yu Zhenwen began the theoretical and technical research on soil moisture measurement and supplementary irrigation in 2000. Over the past decade, the team has conducted a large number of studies and experiments on the effects of different irrigation conditions on wheat yield, quality and nutrition demand from the aspects of crop physiology, crop nutrition and ecology, analyzed the water requirement of wheat in each critical growth period, and determined the optimum water demand. It is found that sowing, jointing and flowering are the key periods of irrigation in the nine growth stages of wheat, such as sowing, overwintering, turning green, getting up, jointing, heading, flowering, filling and maturing, and high yield can be ensured by quantitative irrigation of 40 cubic meters per mu.

However, due to the different soil moisture in different regions and different periods, the water requirement for crop growth is also different. For example, if it rains a few days before the jointing period, if the irrigation is still 40 cubic meters per mu, it will also cause waste. Yu Zhenwen said. For this reason, the innovation team focused on measuring soil moisture and supplementary irrigation, and determined that the best soil relative water content in the key growth period of wheat should be 70% to 75%, based on which the amount of supplementary irrigation should be considered. it is also clear that the most suitable soil depth for measuring soil water content is 0 to 40 cm. "the study shows that the root system is dense at this depth, and the effect of measuring soil moisture and supplementary irrigation with this data is the best." Academician Yu Zhenwen said that since the amount of water for supplementary irrigation by measuring soil moisture is obviously less than that of traditional irrigation, the amount of nitrogen leached into the deep layer of the soil during water infiltration is also greatly reduced, reducing the pollution of nitrogen to groundwater, which is of great significance to the protection of the ecological environment.

The water-saving effect of the technology of measuring soil moisture and supplementary irrigation has been verified in practice. The experimental results of many places in Shandong and Hebei show that, compared with traditional irrigation, this technique can reduce the amount of irrigation by 35 to 70 cubic meters in different precipitation years, increase water use efficiency by more than 10%, and the grain yield is higher than or equal to traditional irrigation. the yield per mu can reach 550 to 600 kg. According to reports, in the course of the research, the innovation team published 77 research papers, which provided a large number of theoretical basis for further exploring water-saving and high-yield technologies, and they also selected portable domestic soil moisture measuring instruments and formulated a formula for measuring soil moisture and supplementary irrigation, so that technicians can calculate the amount of water needed in wheat fields in a few minutes, which is simple and fast.

In order to ensure the high yield of wheat with the least amount of water, the research group studied and popularized it at the same time. At present, this technology has been demonstrated and promoted in more than a dozen counties and cities in Shandong and Hebei. "according to the calculation of water saving of 37.7m3 per mu of wheat field in Gaocheng, Hebei Province this year, if it is fully promoted in Hebei, 30 million mu of wheat in the province can save more than 1.13 billion square meters of water in one season. This is not only an economic account, but also an ecological account. " According to Academician Yu Zhenwen, the research group is currently studying the combination of soil moisture measurement and supplementary irrigation with the integration of water and fertilizer, and the utilization rate and yield of wheat irrigation water will be further improved in the future, which will play an important role in the sustainable development of agricultural production.