Characteristics Of Soil Respiration, Grain Yield And Water Use Efficiency In Crop Fields Under Different Mulching Modes And Crop Conditions

The diurnal and seasonal variations of soil respiration rate for winter wheat and corn monoculture system on dryland with different mulching modes were investigated through field experiments on Changwu Tableland located in the southern area of the Loess Plateau. Vertical distribution of soil moisture, crop yield, and water use efficiency on farmland for winter wheat and maize under plastic film and straw mulching modes were analyzed. The main conclusions from the study are as follows:The diurnal variation characteristic of soil respiration rate in winter wheat field presented a single peak curve and the maximum value was observed at about 12:00. From turning green to harvest time, soil respiration rate reached a maximum in the jointing stage. Throughout the whole observation period, the averaged soil respiration rate without mulching was 1.6μmol CO₂·m^-2·s^-1. Compared with control treatment (CK), the averaged soil respiration rate with plastic film mulching (1.9μmol CO₂·m- 2·s^-1) was increased by 15%, being a significant difference. In the whole growth period of summer maize, soil respiration rate with plastic film mulching (2.4μmol CO₂·m^-2·s^-1) was increased by 14.5% in comparison with that without mulching (2.1μmol CO₂·m^-2·s^-1) and the difference reached a significant level.In the 0-200 cm soil layer, the mulching treatments, in terms of the averaged soil water content in the main growth stages of winter wheat, were in the order of 9000 kg /hm² straw mulching (14.63%) > 4500 kg /hm² straw mulching (14.17%) > plastic film mulching (13.91%) > straw mulching in summer fallow (13.52%) > non-mulching (13.33%). Such an order indicates that with the two mulching modes, soil can keep a large amount of soil water storage, while it can provide crops with water use for depletion. Additionally, soil moisture content under straw mulching treatment was greater than that under plastic film mulching treatment.Wheat yields under different mulching treatments had significant differences. Wheat yields under the 4500 kg/hm² straw mulching, 9000 kg/hm² straw mulching, and non-mulching treatments were increased by 7.5%, 6.6%, and 6.3% and corresponding wheat yields were 325.5, 375.0, and 307.5 kg/hm².The Analysis of variance to different mulching treatments .The results showed that the differences in economic yield of wheat is due to different coverage measures. Respectively. Water use efficiency under the 9000 kg/hm² straw mulching treatment was increased by 5.7%. The difference was significant (P <0.05). In summary, the 9000 kg /hm² straw mulching treatment gives not only a higher yield, but also higher water use efficiency.By a filed experiment on dryland in the Loess Tableland, the vertical distribution of soil moisture, grain yield, and water use efficiency in a corn field were studied under straw and plastic film mulching treatments in contrast to non-mulching treatment. Results showed that the averaged soil moisture contents in the 0-200 cm profile during different growing periods were 16.2%, 15.4%, and 15.3% for straw mulching, plastic film mulching, and control treatments, respectively, and the differences between straw mulching treatment and others were significant at 0.05 level. Compared with control treatment, corn yields under plastic film mulching and straw mulching treatments were increased by 13.9% (P<0.01) and 5.4% (P<0.05), respectively. Water use efficiency for the crop under plastic film mulching and straw mulching treatments was increased by 12.3% and 7.6% (P<0.05), respectively. The result from the study indicated that plastic film mulching may be better than straw mulching in preserving soil moisture, improving water use efficiency, and increasing grain yield.