Over-application of nitrogen (N) and phosphorus (P), and insufficient supply of potassium (K), have been considered as reasons for restriction of yield increases in North China Plain. Field experiments were conducted to evaluate the effects of nutrient management on yield, nutrient uptake and utilization in Shanxi, Hebei, Shandong and Henan provinces, where the typical winter wheat–summer maize rotation system in North Central China is practiced. The results indicated that improved nutrient management by balanced fertilization based on soil testing and target yield (the optimum treatment, OPT) optimized grain yield, nutrient uptake and nutrient use efficiency compared with those for farmer’s practice (FP). By adoption of our improved nutrient management strategy, yield increased by 0.8–13.7% for wheat and 5.8–18.5% for maize separately and, moreover, N and P input declined by 13% (266 kg N ha–1) and 45% (430 kg P2O5 ha–1), and K input increased by 43% (265 kg K2O ha–1) at the four sites over the FP. The OPT increased partial factor productivity of nitrogen (PFPN) and agronomic efficiency of nitrogen (AEN) at all sites with the exception of Shandong where N rates were generally higher than elsewhere, and improved nitrogen recovery efficiency (REN) across all four sites in this study. The results from this study demonstrated that there is still need and great potential to improve PFPN, AEN and REN further in this intensive winter wheat–summer maize rotation system.

In northwest China the lack of knowledge on soil nutrient fertility and of appropriate nutrient management practices has restricted potato production. Field trials were conducted from 2002 to 2007 to determine the main limiting nutrients for potato (Solanum tuberosum L), and to evaluate the nutrient management practice (NMP) based on an Agro Services International (ASI) systematic approach. Results indicated that average potato yields in nutrient omission plots were in the order 0-N (22.2 t ha-1) ≈ 0-P (22.4 t ha-1) < 0-K (31.5 t ha-1). N deficiency is a general feature of irrigated potato in northwest region, but P and K supply are frequently additional limiting factors. The mean agronomic efficiencies (AE) of N, P and K were 34.4 kg tuber kg-1 N, 32.4 kg tuber kg-1 P2O5 and 41.3 kg tuber kg-1 K2O, respectively, and the mean partial factor productivities (PFP) of N, P and K were 220 kg tuber kg-1 N, 291 kg tuber kg-1 P2O5 and 306 kg tuber kg-1 K2O, respectively. There was a significant negative relationship between AE or PFP of N, P or K and the respective nutrient rate. The positive relationship between yield of nutrient omission plots and PFP and AE suggests nutrient use efficiency is affected by soil indigenous productivity. NMP based on an ASI systematic approach produced significant higher yields, nutrient use efficiencies and economic returns than farmer’s practice.