Effects of straw returning and plastic film mulching on soil environment and rice growth

Objective  To investigate the effects of straw returning and plastic film mulching on soil environment and rice growth.

Method  ‘Jijing 88’ was selected as test material. The field experiments were conducted under three groups of straw returning amount and two kinds of cultivation mode (transplanting with plastic film mulching and transplanting without plastic film mulching) to measure soil temperatures, soil fertilities and rice growth traits.

Result  The soil temperatures at 5 and 10 cm depths were significantly affected by plastic film at tillering stage. The soil temperatures of the treatments with plastic film mulching increased 0.2~2.0 ℃ (5 cm depth) and 0.3~1.7 ℃ (10 cm depth) respectively at the same straw returning amount. Compared with the treatments without plastic film mulching, the total nitrogen contents of soil at 20%, 40% and 60% straw returning amounts significantly increased 0.28, 0.26, 0.14 g·kg^–1 respectively at filling stage, the organic matter contents significantly increased 0.74, 0.65, 0.54 g·kg^–1 respectively at mature stage, the tillering numbers increased 9.1%, 22.7%, 17.4% respectively at late tillering stage, the leaf area indexes significantly increased 19.1%, 17.2%, 22.6% respectively at filling stage, the total accumulations of dry matter increased 4.5%, 31.7%, 16.5% respectively, while the actual yields increased 7.3%, 15.2%, 8.5% respectively in the whole growth period.

Conclusion  Straw returning and plastic film mulching can increase soil temperature, soil organic matter and total nitrogen contents, tillering number, leaf area index and dry matter accumulation. Soil temperature, soil fertility and rice growth perform best while straw returning amount is 40%.