[Effects of tillage and fertility on soil nitrogen balance and greenhouse gas emissions of wheat-maize rotation system in Central Henan Province, China.]

Energy saving, emission reduction, and efficiency improvement are important directions for agricultural development in Central Henan Province, the main grain production area in the Huang-huai-hai Plain. Based on the tillage and fertilization positioning experiment in 2010, we investigated the effects of three tillage methods (deep tillage, shallow tillage, and no-tillage) and two fertilization methods (nitrogen fertilizer and nitrogen fertilizer+organic fertilizer) on soil nitrogen balance and greenhouse gas emissions from 2018 to 2019. The results showed that soil nitrogen accumulation increased with organic fertilizer addition. During wheat and maize maturation, soil total nitrogen accumulation in the 0-60 cm layer was the highest under the treatment of shallow tillage+organic fertilizer, being 8058.53 and 8299 kg N·hm^-2, respectively, being 3.2%-27.4% and 4.3%-7.2% higher than other treatments. The treatment with organic fertilizer addition resulted in nitrogen surplus. The shallow tillage+organic fertilizer treatment led to the highest nitrogen surplus (13.57 kg N·hm^-2), which was 9.52 and 0.18 kg N·hm^-2 higher than deep tillage+organic fertilizer and no tillage+organic fertilizer treatments. Nitrate leaching was the main way of nitrogen losses, accounting for 73.4%-76.9% of the total losses. The amount of nitrate leaching was the highest in deep tillage+organic fertilizer treatment (48.37 kg N·hm^-2), being 18.9%-35.1% higher than other treatments. Results of greenhouse gases emission during 2018-2019 showed that global warming potential was the highest under the treatment of deep tillage+organic fertilizer, which was 33070 kg N·hm^-2, being 6.6%-26.8% higher than other treatments. The treatment of organic fertilizer addition increased the emission of N₂O and CO₂ and reduced the absorption of CH₄. The annual grain yield was highest under the treatment of deep tillage+organic fertilizer, which was 5.0%-17.1% higher than other treatments. The crop harvest index was the highest under the treatment of shallow tillage+organic fertilizer. The recommended cropping mode in Central Henan Pro-vince is shallow tillage+organic fertilizer, which could ensure crop yields, maintain soil nitrogen balance, and reduce greenhouse gas emissions.