Straw Return with Reduced Nitrogen Fertilizer Maintained Maize High Yield in Northeast China

Crop residue management is a major concern in China. Returning straw to the field has been promoted to reduce chemical fertilizer input and increase crop yield. For this, the present study as a part of an existing long-term field experiment was conducted including four treatments: (1) Maize straw return with reduced nitrogen, phosphorus, and potassium fertilizers (straw + NPK; SNPK); (2) NPK fertilizers; (3) PK fertilizers; and (4) no fertilizers added (nF) in the years of 2016 and 2017. Results showed SNPK and NPK produced similar grain yield over the two years (12,485 vs. 12,754 kg ha−1), which was approximately 3-fold of PK and nF (4763 vs. 3858 kg ha−1). The yield difference was not significant between SNPK and NPK and between PK and nF. The effect of straw return on plant productivity is related to precipitation. In contrast to total carbon (C), nitrogen (N), and phosphorus (P), K was lost from leaf, stem, and grain. Dynamics of plant N post-flowering is critical to determine maize yield and yield components relative to C, P, and K. Dynamics of P and K in leaf were more correlated with yield than in stem, implying the significance of leaf productivity in determining grain yield. These results indicate that combination of NPK fertilizers is critical for increasing grain yield in maize. Crop straw return with reduced NPK fertilizers will help to improve yield and reduce chemical fertilizer input in the long run.