[The planting effect of cover crop in Sanjiang Plain, Northeast China]. / 东北三江平原覆盖作物种植效果.

The planting effect and the planting potential of 12 cover crops (Leguminous: alfalfa, smooth vetch, hairy vetch, red clover, white clover, common vetch; non-leguminous: sudangrass, green radish, Nitro radish, rape, kale, endive) in the Sanjiang Plain of Northeast China were comprehensively evaluated by soil penetration resistance, pre-winter biomass, root characteristics, and plant nitrogen accumulation. The results showed that all the 12 cover crops grew normally during the experimental sowing period. Compared with the control, all the cover crops successfully reduced soil compactness. The planting of green radish, nitro radish, and sudangrass decreased soil penetration resistance by 47.1%, 43.4% and 33.4%, respectively. The pre-winter total fresh biomass of cover crop populations was between 3.38 and 13.98 kg·m-2, and the total dry matter mass was between 0.78 and 2.43 kg·m-2. The biomass of non-leguminous cover crops was significantly higher than that of the leguminous cover crops. The group roots of radish, rape and endive had large volumes. In particular, the nitro radish roots had a vo-lume of 4018.5 cm3·m-2, and the root system of sudangrass extended over the widest horizontal range. The ash content of leguminous cover crops was significantly lower than that of non-leguminous species, which could provide more organic matter with high decomposability. The total nitrogen accumulation of cover crops varied from 18.72 to 53.09 g·m-2. Kale and endive accumulated the highest amount of nitrogen and large biomass, which could facilitate nitrogen fixation and accumulation. According to the type of main crops in Sanjiang Plain and canopy structure, planting leguminous (clover, vetch, and alfalfa) and non-leguminous (radish, kale and sudangrass) cover crops to plant inter-row or in a line mixed cropping pattern could regulate soil structure and promote nutrient cycing, with positive effects on the fertility of black soil in the Sanjiang Plain.

[Effect of long-term straw mulching and no-tillage on physical properties of meadow soil in cold region.] / é•¿æœŸå è€•ç§¸ç§†è¦†ç›–å¯¹å¯’åœ°è‰ç”¸åœŸåœŸå£¤ç‰©ç†æ€§è´¨çš„å½±å“.

The effects of different straw returning technology and farming system on soil physical properties is not clear in Heilongjiang Province, which is located in middle temperature zone with large amount of straw. Here, the effects of straw mulching on soil physical properties in meadow soil under no tillage conditions were studied in field experiments for eight consecutive years (2010-2017). The no straw covering (0%), 30% coverage (30%), 60% coverage (60%) and 100% coverage (100%) were disposed in the experiment. The results showed that straw mulching under no tillage significantly increased soil bulk density by 0.10-0.20 g·cm-3, which increased with the increases of coverage amount. Straw mulching increased soil solid fraction by 2.5%-7.8%. Soil temperature decreased with the increases of coverage amount, and this trend was more apparent on the surface of soil. The temperature reduction in 0-5 cm soil layer was 1.87-2.90 ℃. Soil water content significantly increased with the increases of straw mulching, with an enhancement of 6.4%-10.2%. Straw mulch decreased the total porosity and diameter of >0.05 mm aeration pores, increased the effective pore size of 0.05-0.002 mm, with the magnitude of such effects being positively dependent on coverage amount. There was no significant effect of straw mulching on inactive porosity of soil. Long-term straw mulching increased soil compaction and soil moisture, reduced soil temperature and total soil porosity, and increased soil available porosity in 0-5 cm soil layer.

[Variation of rhizosphere environmental factors of sugarbeet seedlings under Na2CO3 stress and their correlation.] / Na2CO3èƒè¿«ä¸‹ç”œèœå¹¼è‹—æ ¹é™ åœŸå£¤çŽ¯å¢ƒå› å­çš„å˜åŒ–åŠå ¶ç›¸å ³æ€§.

To study the effect of saline-alkali stress on dry mass, rhizosphere soil enzyme activities and soil microbial quantities, pot experiments were designed two sugar beet varieties, 'KWS0143' (strong tolerance to saline-alkali) and 'Beta464' (weak tolerance to saline-alkali) planted in different Na2CO3 concentrations [0% (control), 0.4%, 0.8% and 1.2% of soil], and the dry mass of seedlings,soil enzyme activities and amount of microbiology in soil were recorded. The results showed that compared with the control, the dry mass of seedlings was significantly increased in the treatment of 0.4% Na2CO3, while it was significantly decreased in the 0.8% and 1.2% Na2CO3 treatments. Significant differences among treatments were observed. The soil urease, alkali phosphatase and peroxidase activities in the root rhizosphere of seedlings presented a similar tendency under different concentrations of Na2CO3. Compared with the control, the enzyme activities with the treatment 0.4% Na2CO3 were not significantly enhanced, while those in the treatment of 0.8% and 1.2% Na2CO3 were significantly reduced. All the soil enzymes' activities in 'KWS0143 were higher than in 'Beta464'. The 0.4% Na2CO3 did not lead to significant change of soil microbial community, but 0.8% and 1.2% Na2CO3 sharply decreased the amount of soil bacteria, fungi and actinomycets (P<0.05). The amount of rhizosphere soil microbe in 'KWS0143' was higher than in 'Beta464'. There were significantly positive correlation among the dry mass, soil enzymes and soil microbe of the two varietie. Path coefficient analysis showed the determinant coefficient of 'KWS0143' dry mass was in order of sctinomycetes > bacteria > peroxidase > urease > fungi > alkali phosphatase, while that 'Beta464' dry mass was in order of actinomycetes > peroxidase > urease > fungi > alkali phosphatase > bacteria.