ABSTRACT Tillage is an important management tool for tackling and promoting water conservation and improving crop yield. As one of the important nutrients in plant growth, K is involved in important processes such as osmoregulation, photosynthesis and metabolite transport, and plays a particularly critical role in improving crop yield and quality. In the long-term positioning platform of the tillage method, a 2-yr field experiment was conducted in 2019-2020 in maize (Zea mays L.) Three tillage methods: conventional tillage (CT), subsoil tillage (ST), and no-tillage (NT) and two planting densities 6×104 (D1) and 9×104 plants ha-1 (D2) were set up in the experiment. The results showed that yield and K translocation efficiency (KTE) were significantly higher in NT than in CT at D1 (by 4.7% and 12.2%) and D2 (by 14.0% and 13.9%), respectively. At maturity stage in 2019, population DM accumulation after silking (DMA) was significantly higher in NT (by 11.0% and 16.9%) than in CT at D1 and D2. Correlation analysis revealed that yield was significantly positive correlated with ears (r = 0.57***) and DMA (r = 0.64***). Potassium translocation and K harvest index were positively correlated with KTE. Under spring drought year, the long-term no-tillage had a significant yield increase, mainly through the increase in 1000-kernel weight. The increase in K efficiency was mainly through the influence of DM accumulation and distribution, and K accumulation in grain.

ABSTRACT For the synergistic improvement of soil fertility and rice yields in a cold region, we investigated the effects of plastic mulching with different straw incorporation rates on the rice yield and nitrogen use efficiency in a rice growing area of a cold region. The field experiment was conducted using the Jijing 88 rice cultivar, and set up four straw incorporated treatment: 20% (S1), 40% (S2), 60% (S3) and 100% (S4) under two conditions: mulching (M) and without mulching (NM). The results showed that under the same straw incorporation rates: (1) Plastic mulching increased the total soil nitrogen and organic matter contents while improving the grain yield; the yield increases were 2.8–14.9% in 2016 and 1.4–12.3% in 2017. (2) The mulched treatment improved the net photosynthetic rate, the maximum tiller number, the crop growth rate of the later growth stages, and the shoot dry weight. (3) The recovery efficiency, agronomic efficiency, and partial factor productivity of the nitrogen applications were all higher under the mulched treatment than under the non-mulched treatment. In a comparison of the different straw incorporation treatments, above three indicators consistently increased before they decreased, and significantly higher levels were reached under the 40% straw incorporation treatment with mulching than under the other treatments.