In order to maintain high yields and protect the environment, the replacement of chemical fertilizers with organic ones has received increasing attention in recent years. A 2-year field experiment (2015–2016) was carried out to assess the effects of substituting equal amounts of mineral fertilizer with organic manure on the yield, dry matter (DM), and nitrogen (N) uptake of spring maize ( Zea mays L.) and on the mineral N (N min ) distribution in the soil profile. The treatments included chemical fertilizer; different amounts of maize straw, cow manure, and chicken manure; and an unfertilized control (CK). Compared with the chemical fertilizer treatments, equal amounts of substitutions with cow manure or chicken manure increased production, and a 25% nutrient substitution resulted in the best yield increase. Straw return had no effect on maize production, and 100% straw return resulted in reduced production. The N accumulation and DM content both exhibited a slow-fast-slow growth trend throughout the various growth stages, and the average N uptake and DM accumulation in response to the treatments followed the order of chicken manure > cow manure > chemical fertilizer > straw return > CK. The N min content in the profile not only increased as the N min application rate increased but also showed greater increases at certain depths than at the surface, indicating that excessive N led to leaching. These results suggest that an appropriate proportion of organic substitution not only provides enough nutrients but also improves the soil environment and leads to increased yields. This technique represents a practical method of continuously increasing production and reducing the risk of N leaching.

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The effect of different long-term (2001-2016) tillage practices on soil nitrogen forms in different soil layers were studied to provide a scientific basis for evaluating soil fertility and establishing rational fertilization measures. Soil contents of total nitrogen (TN), particulate organic nitrogen (PON), microbial biomass nitrogen (MBN), water soluble organic nitrogen (WSON), NO3-N content, NH4-N content ammonium nitrogen and organic acid nitrogen component contents were measured under notillage (NT) and mould plow (MP) treatments based on a long-term (16 year) conservation tillage experiment in Northeast China. The results showed that no-tillage increased soil total nitrogen, active nitrogen, inorganic nitrogen and organic nitrogen content, which varied with soil depth. Compared with MP, NT significantly (p < 0.05) increased total nitrogen and active nitrogen content in the surface soil (0-30 cm); TN, PON, MBN and WSON increased significantly (p < 0.05) by 28.32%, 23.07%, 15.13% and 25.21% in 0-5 cm and by 10.17%, 19.4%, 15.97%, and 31.33% in 5-10 cm, respectively. For soil inorganic nitrogen, the content of ammonium nitrate at 0-5 cm and at 5-10 cm under NT was significantly (p < 0.05) higher than that of MP by 28.1% and 32.13%, respectively, and the content of ammonium nitrogen in soil at 0-5 cm was significantly (p < 0.05) higher, by 12.86%, than that of MP. No-tillage significantly increased the content of total hydrolysable nitrogen, hydrolysable ammonia nitrogen, hydrolysable amino acid nitrogen and hydrolysable unidentified nitrogen in the 0-10 cm soil layer, but no significant effect was found on the content of hydrolysable amino sugar nitrogen. Soil nitrogen content was closely related to tillage practices. These results suggest that no-tillage was beneficial in augmenting soil nitrogen supply capacity by increasing soil total nitrogen, active nitrogen, inorganic nitrogen and organic nitrogen content.

Improving nitrogen use efficiency (NUE) has great significance for agriculture sustainable development and reducing environmental pollution. The effects of Mg fertilizer combined with straw return on yield, N uptake, and NUE of spring maize (Zea mays L.) were investigated for two consecutive years. The treatments included JM3 (straw + magnesium fertilizer), JM0 (straw + no magnesium fertilizer), WM3 (no straw + magnesium fertilizer), and WM0 (no magnesium fertilizer + no straw). The application of Mg fertilizer significantly improved yield. The application of straw and Mg fertilizer together improved yield even more significantly; the grain yield of the JM3 treatment was 5.28% higher than that of the WM0 treatments. The highest total N uptake was obtained from the JM3. Nitrogen remobilization from vegetation organs to grain was highest in the JM3 treatment. The agronomic efficiency of fertilizer nitrogen (AEN), recovery of applied fertilizer nitrogen (REN), partial factor productivity of fertilizer nitrogen (PFPN), and nitrogen harvest index (NHI) responded significantly to straw return and Mg fertilizer. The AEN, REN, PFPN, and NHI values for the JM3 treatment were 15.35, 24.63, 5.28, and 2.31% higher on average, respectively, than those for the WM0 treatments. Generally, these outcomes indicated that there was an interaction between Mg fertilizer and maize straw. The application of Mg fertilizer with straw return significantly improved the grain yield, N uptake, and NUE of maize plants. The combination of straw return and Mg application is a practical method for increasing maize production and supporting sustainable agriculture.

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BACKGROUND In recent years, shallow‐buried drip irrigation in spring maize production has gradually replaced drip irrigation under plastic films and has become a common irrigation method in semiarid areas of northern China. RESULT Two years of field experiments were carried out in the semiarid area of western Jilin province to compare the two drip irrigation methods in the spring maize production system. The treatments included MW1 (drip irrigation under mulch + moderate irrigation amount), MW2 (drip irrigation under mulch + high irrigation amount), SM1 (shallow‐buried drip irrigation + moderate irrigation amount), and SM2 (shallow‐buried drip irrigation + high irrigation amount). The maize yields were significantly higher under mulch than under shallow‐buried drip irrigation, but there was no interaction between mulch and the irrigation amount. Drip irrigation under mulch greatly improved spring maize N, P and K uptake compared with that under shallow‐buried drip irrigation. The agronomic‐use efficiency, recovery‐use efficiency, and partial factor productivity were ranked in the order of MW2 > MW1 > SW2 > SW1. The water‐use efficiency of drip irrigation under mulch was 7.44% and 6.82% higher than that of shallow‐buried drip irrigation under the moderate and high irrigation levels, respectively. However, considering the costs of the plastic mulch, there was no significant (P < 0.05) difference in economic benefits between the SW and MW treatments. CONCLUSION Drip irrigation under plastic film provides greater advantages for production, but shallow‐buried drip irrigation may be a suitable method for farmers until fertigation technology is further optimized and the problem of plastic film pollution is solved. © 2020 Society of Chemical Industry

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