Nutrient resource quantity of crop straw and its potential of substituting

Objectives The paperis aimed to find out the quantity of straws and assess their potentials as nutrient resources in China, which is of great significance for making full use of straw resources, improving fertilizer use efficiency, achieving zero growth of chemical fertilizers and ensuring national food security.

Methods Rice, wheat, maize, soybean, potato, peanut and rapeseed were chosen as the research objects. Based on agricultural statistics and published literatures, the amount of crop straws and the contained nutrient resources were estimated in 2015. The optimum fertilizer application rates of different crops in different regions were analyzed, and the proper percents of straw nutrient were proposed for the substitution of chemical nutrients through returning to field in China.

Results In 2015, the amount of the main crop straws in China was 718.7853 million tons, containing 6.256 million tons of N, 1.979 million tons of P₂O₅ and 11.595 million tons of K₂O, respectively. The largest straw nutrient resources were from rice, wheat and maize, accounting for 33.1%, 14.5% and 34.2% of the total nutrient resources. Of the other straws, rapeseeds contained the largest nutrient amount, which was accounted for 7.6% of the total resources. The highest straw mass was produced in North China Plain and the Middle-lower reaches of Changjiang River, accounting for 26.4% and 26.2% of the whole yields across China, respectively. The total nutrient amounts were the highest in the straws of Heilongjiang Province, followed by those of Henan and Shandong Provinces, accounting for 10.3%, 9.5% and 6.8%, respectively. In 2015 in China, the main crops sown area was 120 million hectares, the economic yield was 630 million tons, which demand theoretically N, P₂O₅and K₂O inputs of 15, 6 and 17 million tons, respectively. In case of the total straws be returned to fields, the nutirents brought to fields would be as much as N 54.4 kg/hm², P₂O₅15.5 kg/hm²and K₂O 88.1 kg/hm², which were accounted for 38.4%, 18.9% and 85.5% of the chemical fertilizers, respectively.

Conclusions The crop straw quantities and the contained nutrient resources are tremendous in China, showing regional characteristics in straw sources and amount. Exploring and making full use of straw nutrient resources will provide an effective and environmental friendly resolution for realizing zero chemical fertilizer increase and improving efficiency of agricultural production.