Abstract:

To explore the influence of large-scale rice-duck co-cultivation for successive years on paddy soil properties, and rice yield and quality, two treatments were set up for 10 consecutive years (2010 to 2019) of large-scale rice-duck co-cultivation and conventional high-yield rice cultivation. The indexes of soil nutrient content, rice yield structure, rice quality, heavy metal content and pesticide residues in paddy fields were tested for comparison. The results showed that compared with conventional rice cultivation, the soil bulk density decreased by 5.65% after years of rice-duck co-cultivation, and the contents of organic matter, total nitrogen, available phosphorus and available potassium in 0-10 cm topsoil increased by 8.71%, 14.29%, 9.68% and 8.34%, respectively, which improved the fertility of paddy soil. The number of grains per panicle, the seed setting rate and the 1000-grain weight of the rice-duck co-cultivation increased by 11.3%, 2.9% and 3.2%, respectively, which was beneficial to the formation of large panicles, but the reduction of effective panicles reduced rice yield by 16.4%. The rate of brown rice and milled rice increased by 4.8% and 3.6%, respectively, the chalky grain rate and chalkiness degree decreased significantly, and the protein content increased by 7.5%. At the same time, the amylose content and hard gel consistency were not significantly different from those of conventional field and the overall rice quality was improved. In the two treatments, the contents of heavy metal elements in the soil and the contents of heavy metal elements and pesticide residues in rice all meet the green standards. Therefore, rice-duck co-cultivation for successive years could improve soil properties, soil fertility and rice quality, but the reduction of effective panicle can significantly reduce rice yield.

Key words: rice-duck co-cultivation, soil nutrients, rice yield, rice quality, heavy metals, pesticide residue