Response of corn yield to long-term straw return patterns in Hexi oasis irrigation area under plastic film mulching condition

Objectives Returning ways of straws affect their yield promotion efficiency. We studied the cumulative effect of different straw return patterns on the corn yield in Hexi oasis irrigation area.

Methods A localized field experiment was conducted in the Hexi oasis irrigation area from 2011 to 2020. The seven treatments included no straw return (CK), half amount of harvested corn straws buried into soil directly (1/2WB), or covered on soil surface directly (1/2WM); half or whole amount of harvested corn straws were crushed and then buried into soil (1/2CB, CB), or covered on surface soil (1/2CM, CM). All the straw were returned in strips between corn rows and covered with plastic film at last. The corn yields were recorded every year for the calculation of cumulative contribution rate of straw return. In 2020, the SPAD values of the bottom second leaf were monitored at five main growth stages of corn. At harvest, plant growth indexes, yield and yield components were investigated, and the contribution rate of straw return to cumulative yield was calculated.

Results The CB and CM treatments increased (P<0.05) grain number per spike, 100-grain weight, plant height, stem diameter, spike diameter, spike length, effective spike length and harvest index of corn, reduced (P<0.05) the length of corn bald top, and CB treatment also increased spike number of corn, thus significantly increased grain yield. In 2011, all the straw return treatments had no significant effect on leaf SPAD values at seedling, jointing, large bell-opening and tasseling stages (P>0.05), compared with CK. In 2020, CB and 1/2 CB treatments recorded significantly higher SPAD values at seedling, jointing, large bell-opening, tasseling and silking stages (P<0.05). Straw return had cumulative effect on corn yield, and CB treatment exhibited the highest contribution rate (9.33%−14.15%), followed by 1/2CB treatment (7.17%−12.25%), and CM treatment (9.19%−10.14%).

Conclusions Straw return in strips and covered with plastic film could coordinate the interrelationship between plant growth and grain development, maintain high photosynthetic ability across the growing stage, thus significantly increase grain yield. The continue of straw return is conducive to increase the yield advantages. Comparing the returning patterns, the yield effect of crushed straw returning into soil is better than whole stalk covering on surface soil, and whole amount of straw return is better than half amount.