Effect of Straw Utilization Methods on Japonica Rice Production in Northern China

  Objective  Effect of various means to utilize straws after rice harvest on production and yield of Japonica rice in northern China was evaluated for optimal farm waste management.

  Method  Seedlings of Shennong 265 were transplanted for the experimental cultivation using the conventional fertilization method, a direct straw reclamation in soil at a rate of 6 t·hm^-2, the application of straw biochar at a rate of 2 t·hm^-2, or the application of straw biochar at a rate of 40 t·hm^-2. Rice production and grain yield at harvest were recorded for analysis.

  Result  Adding the cut straws directly back to the field lowered the dry matter accumulation in the grains in the following season that significantly decreased the material output and contribution rates by the leaves by 41.19% and 34.69%, respectively. The grain count per panicle, 1 000-grain weight, panicle number, and grain yield of the rice plants were all negatively affected under the direct straw addition method. The biochar application at the higher rate also reduced dry matter accumulation in the grains with significantly decreased material output by the leaves (21.41% reduction) and stems/sheaths (17.43% reduction). The grain count per panicle was lower than the conventional method as well. On the other hand, when the biochar application was implemented at a lower rate, i.e., 2 t·hm^-2 rather than 40 t·hm^-2, the dry matters increased 11.68% on the material contribution rate by the leaves, along with the positive effects observed on the grain count per panicle, 1 000-grain weight, panicle number, and yield of the rice grown by using the method.

  Conclusion  The waste utilization by adding straw biochar at 2 t·hm^-2 to the soil appeared plausible for rice production in northern China.