Abstract
Abstract: PAM (polyacrylamide) has been extensively used for dewatering sewage sludge, potable water treatment, paper manufacturing, and coal and mine processing. PAM can decrease soil evaporation, improve soil structure, increase soil moisture, reduce surface runoff and soil erosion, strengthen soil and water conservation, but little is known about its effects on crop growth, crop output value and water use efficiency in agriculture production. Northern China is rich in light and heat, and has vast land resource, but less rainfall and soil moisture limits the ecological environment construction and agricultural development. The experiment was conducted to study the influences of PAM on soil water use efficiency, crops yields and crops output value in fields. Watermelon, potato, maize and millet were selected as test crops in semi-arid regions of northern Shaanxi, China. Meanwhile, spring wheat, maize, sunflower and tomato were as test crops in arid region of Hetao irrigation district, Inner Mongolia, China. Different crops without applying PAM were taken as control in different regions. The crop yield, crop output value, water use efficiency and water production rate of different crops were monitored and analyzed. In semi-arid regions, the results showed that the yield of watermelon, potato, maize and millet increased by 36.76%, 24.83%, 20.20% and 30.78%, respectively; increased value was 37 050.00, 11 571.84, 1 615.26 and 3077.00 yuan/hm2, respectively; output value increased by 36.32%, 23.04%, 9.37% and 10.18%, respectively; water use efficiency increased by 30.15%, 18.83%, 13.42% and 6.24%, respectively; water production rate increased by 30.57%, 22.97%, 16.79% and 11.66%, respectively. Meanwhile, in arid region, the yield of spring wheat, sunflower, maize and tomato increased by 18.56%, 12.82%, 13.65% and 16.54%, respectively; increased value was 1 990.24, 4 541.92, 2 076.60 and 7 248.60 yuan/hm2, respectively; output value increased by 12.748%, 10.70%, 9.53% and 14.71%, respectively; water use efficiency increased by 13.49%, 17.03%, 12.96% and 25.12%, respectively; water production rate increased by 16.14%, 11.62%, 11.79% and 14.85%, respectively. In semi-arid regions, watermelon and potato had higher increasing rate of output value and water use efficiency, and more increased value per unit area. Meanwhile, in arid region, the increasing rate of yield and output value of spring wheat was higher than that of sunflower, but the increased value per unit area was significantly lower than that of sunflower and tomato. Tomato and sunflower had higher increased value per unit area, water use efficiency and increasing rate of output value in arid region. According to the water use efficiency, output value and other indicators of different crops with applying PAM, watermelon and potato should be the preference crops for application and popularization of PAM in semi-arid region, and tomato and sunflower should be the preference crops in arid region of northern China.
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