Winter wheat grain yield in response to different production practices and soil fertility in northern China

Scientific production management in the field is the main measure to increase crop yield. Different production practices and soil fertility has profound effects on the yield of wheat (Triticum aestivum L.) in northern China. A meta analysis of 6470 observations from 175 research papers for studies done across 77 locations in northern China was undertaken with respect to grain yield (GY) of winter wheat as influenced by soil organic matter (SOM), total nitrogen (TN), available phosphorous (AP), and available potassium (AK) under common production practices. The results were as follows: (1) Mulching and tillage increased GY by 13.2 and 7.8% relative to that from conventional tillage, respectively. (2) GY, spike number (SN), and grain number per ear (GNE) were markedly affected by mineral nitrogen (N) application rate at 200-285 kg ha(-1). (3) Application of N affected GY nearly three times more than mulching combined with tillage did, and the effect of N being evident mainly in SN and GNE. (4) SOM at 10-14.9 g kg(-1), TN at 1-1.5 g kg(-1), AP at 10-19.8 mg kg(-1), and AK at 100-200 mg kg(-1) were the most effective soil fertility levels to improve wheat GY among all the research levels.