The Tradeoff between Maintaining Maize (Zea mays L.) Productivity and Improving Soil Quality under Conservation Tillage Practice in Semi-Arid Region of Northeast China

Conservation tillage has received strong support globally to achieve food security and minimize environmental impacts. However, there are comprehensive debates on whether it can achieve the synergy between maintaining crop yields and improving soil quality. To this end, a field experiment under continuous maize (Zea mays L.) cropping was conducted in northeast China. The treatment included rotary tillage with straw removal (CK, conventional tillage) and rotary tillage, subsoiling tillage, and no tillage with straw retention (CR, CS, and CN, respectively). Maize yield and a set of soil physio-chemical indicators in relation with soil quality were measured during 2017 to 2021. Results showed that CN significantly reduced the maize yield by 24.9%, 23.1%, and 19.5% on average compared to that with CR, CK, and CS treatments, respectively. CN and CS significantly increased the ratio of >2 mm soil aggregates and soil geometric mean diameter (GMD) in the 0-20 cm soil layer compared those of CK and CR treatments. However, CN and CS treatments had a higher soil bulk density and soil compaction in the 0-20 cm layer compared to those with CK and CR treatments. Soil organic carbon and total nitrogen in the 0-20 cm layer under CN and CS were higher than those with CK by 5.1-15.0% and 8.5-15.7%, whereas soil NH4+ was lower by 9.1-13.9% correspondingly. CN also reduced the soil temperature during the early-growth stage of maize. Importance analysis indicated that soil temperature, bulk density, and available nitrogen were the key factors affecting maize yield. Overall, no tillage with straw mulching could improve soil stability and soil fertility but reduced maize yield. Alternatively, minimum tillage (e.g., subsoiling tillage) with straw mulching might be a suitable practice as it maintains the maize yield and improves soil quality compared to those with conventional tillage practices in the semi-arid region of northeast China in the short term.