Advantages of semi-arid rice cultivation

Semi-arid cultivation means that in the paddy field, according to a certain specification, the rice is planted on the water level line or box on both sides of the ridge, irrigated in the ditch, and the water level is adjusted according to the different growth stages of rice. A new rice planting method of infiltration irrigation. According to the ecological characteristics of farmland and applying the principle of natural no-tillage and the theory of soil bio-thermodynamics, it is a new rice cultivation technique, which is suitable for winter paddy field, especially in deep foot field, cold soaking field, rotten mud field and large fertile field. Therefore, the area has expanded rapidly over the past few years. In 1987, the popularized area of Sichuan, Guizhou, Hubei, Guangdong and Fujian provinces reached 5.1293 million mu, with an average increase of 70kg of grain per mu and an increase of 55.50 yuan.

The reasons for increasing yield of semi-arid cultivation:

① accelerates the exchange of matter and energy between soil and the outside world. After ridging, the soil temperature is increased, the micro-topography is artificially changed, the ripe soil layer for rice growth is thickened, and the total surface area of the field is expanded (the total surface area between soil and air is increased from zero to 410 square meters / mu). The rapid exchange of material and energy between the soil and the outside world greatly increases the area of the soil receiving light and absorbing solar radiation heat, and accordingly expands the heat dissipation area of the soil. In addition, the water content in the soil is less than that in the flat field, the soil heat capacity decreases, the soil temperature is easy to increase (2 ~ 3 ℃ higher than that of the flat crop), and the temperature difference between day and night is also larger. It is beneficial to overcome the disadvantages of cold, overcast and rotten fields in early spring due to low temperature, and the large temperature difference between day and night is beneficial to reduce the respiratory consumption of rice plants, increase the accumulation of dry matter in the body, and lay a material foundation for the growth of rice.

② changes the form of water movement to coordinate the contradiction of water vapor. After ridging, the surface water changed from the original multi-directional turbulence in the flat field to the directional flow of ridges and furrows, and the gravity water in the upper soil of the ridge was basically eliminated, forming a movement form dominated by the rise of capillary water, so that the natural structure of the soil could be maintained. the soil will not dry up and crack, nor will it be dispersed into a muddy state by water (flooding), showing a loose and porous layer, and the ventilation can be obviously improved. The amount of air entering the soil is increased (Eh is 160-180 millivolts higher than that of flat cropping fields), the contradiction of water vapor is more coordinated, the gasification potential is enhanced, and the total amount of reducing substances can be reduced by 75-80%, which is beneficial to eliminate the harm of toxic substances to rice roots.

③ enhances soil enzyme activity, promotes the activity of aerobic microorganisms, and improves soil fertilizer supply capacity. Due to the obvious improvement of thermal and aeration conditions in the soil, the total amount of aerobic microorganisms in the soil is 1 to 5 times more than that in the flat cropping field, and the activity of hydrogen peroxide (H2O2) is high, which reduces the harm of soil reductants to rice roots and increases the secretion of rice roots, thus improving the enzyme activity of microorganisms in the rhizosphere, which is beneficial to the mineralization of organic matter and the transformation of mineral elements in the soil, the increase of soil available nutrients and the rapid decomposition of organic nutrients. The decomposition of organic nitrogen is fast, the nitrogen metabolism is strong, the soil nitrogen supply capacity is improved, and the transport is convenient. According to the determination, total available nitrogen and nitrate nitrogen increased, while ammonium nitrogen decreased. Because nitrate nitrogen is easy to be leached and denitrified, ridge cultivation can not reduce the amount of nitrogen fertilizer, especially heavy application of surface fertilizer and early application of tiller fertilizer. In addition, due to the low soil water content, the increase of pH value, the increase of soil available zinc content and the decrease of available phosphorus, attention should be paid to the application of phosphate fertilizer.