微孔深松耕降低土壤紧实度提高棉花产量与种籽品质

长期传统耕作导致土壤紧实形成犁底层是影响农田土壤质量和作物生长的关键障碍因子之一。为解决这一问题,于2013年4月至2014年5月在山西运城南花农场开展为期1 a的大田试验,对比研究微孔深松耕技术和旋耕机旋耕15~20 cm的传统耕作方法对土壤紧实度以及棉籽品质性状和生长发育的影响。结果表明:微孔深松耕技术较传统耕作方式,棉花苗期犁底层40 cm处土壤紧实度由9 069.70降低到558.80 k Pa,吐絮期犁底层40 cm处的土壤紧实度由8 089.70降低到1 174.20 k Pa,吐絮期0~40 cm土层中微孔深松耕土壤容重最大为1.05 g/cm3,传统耕作最大为1.56 g/cm3;在30 cm土层中,微孔深松耕的总根量比传统耕作方式多187.03%;微孔深松耕处理棉株棉铃的5室铃率较传统耕作增加15.00%,每个棉瓤的种子数平均增加1~2粒;棉籽的籽指、密度、绒长均明显增加,脂肪含量显著降低(P0.05),蛋白质含量显著增加(P0.05),单株铃数比传统耕作增加6.34%,铃质量增加5.75%,皮棉产量增加10.12%。效益分析表明,采用微孔穴深松耕作种植棉花,每公顷净收益增加3 338.00元。该研究揭示了微孔深松耕作可有效打破犁底层,具有疏松土壤紧实度,并提高棉籽品质增加棉花产量,为该项技术应用于生产提供试验依据。

Microhole subsoiling decreasing soil compaction, and improving yield and seed quality of cotton

Abstract: During long-term conventional tillage, frequent use of heavy farm machinery in field operations results in narrow soil effective (plow) layer and thick plow pan. The plow pan resulting from soil compaction is a key constraint on soil quality and crop growth in cultivated land. To address this problem, microhole subsoiling is an alternative to conventional tillage. By reducing the tillage area, microhole subsoiling breaks the plow pan and increases soil permeability, which facilitates root growth into deeper soil, improves uptake of water and nutrients by plant, and reduces surface soil structure damage. Presently, the effects of microhole subsoiling on soil environment, cotton growth and development, and seed quality traits are not well understood. A comparative study of microhole subsoiling and conventional tillage (control) was conducted by one-year field experiment on the Nanhua Farm in Yuncheng, Shanxi Province, China (April 2013 to May 2014). Microhole subsoiling was implemented by vertical drilling using a soil auger with the diameter of 8 cm. Vertical subsoiling was conducted to 80 cm depth in a hole-like pattern at specific intervals. In microhole-subsoiled plots, the actual tillage area was about 239.2 m2/hm2, i.e., only 2.39 % of total area. At the seedling stage, soil compaction remained almost unchanged and less than 558.8 kPa at 0-40 cm depth in microhole-subsoiled plots, whereas that in control plots was significantly higher and up to 9 069.7 kPa at >20 cm depth. At the boll opening stage, soil compaction increased slowly up to 1 174.2 kPa in microhole-subsoiled plots, while that in control plots reached a maximum of 8 089.7 kPa. Meanwhile, soil bulk density in microhole-subsoiled plots remained lower and decreased from 1.56 to 1.05 g/cm3 at >35-40 cm depth. Owing to the loosening of deeper soil, microhole subsoiling effectively induced cotton roots to go deeper. The main root reached the depth of over 80 cm depth in microhole-subsoiled plots and <70 cm depth in control plots. At the depth of below 30 cm, microhole subsoiling doubled root biomass (19.77% of total root biomass) and increased lateral roots (32.62% of total lateral root) compared with the control (9.81% of total root biomass and 19.42% of total lateral root). The 5-room boll rate was 15% higher and the number of seeds per cotton pulp was greater by from 1 to 2 in microhole-subsoiled plots than in control plots. At the second and fifth seed positions, cotton seed index, proportion and fiber length were significantly higher in the former than in the latter by 0.03 g, 0.035 g/cm3 and 2.25 mm, respectively. Similar trends were observed in the emergence and healthy seedling rates, i.e., 1.01% and 2.27% higher in microhole-subsoiled plots than in control plots, respectively. The mortality and weak seedling rates were 0.92% and 1.41% lower in the former than in the latter. Seed protein was significantly higher (P<0.05) while seed fat content was significantly lower (P<0.05) in microhole-subsoiled plots than in control plots. Additionally, the number of bolls per plant, boll weight and lint yield were 6.34%, 5.75% and 10.12% higher in microhole-subsoiled plots than in control plots, respectively. Benefit analysis showed that compared with the control, microhole subsoiling improved the net income of cotton cultivation by 3 338.00 yuan/hm2. This benefit was mainly due to cotton yield increased significantly, seed sowing rate reduced effectively and relatively less input of tillage cost. This study revealed that that microhole subsoiling could effectively break local plow pan, thus alleviating soil compaction and reducing soil bulk density. The improvements of soil environment would induce cotton roots to go deeper and increase the number of lateral roots, thus improving seed quality and cotton yield. Microhole subsoiling overcame the environmental problems caused by conventional tillage regarding high energy consumption and severe soil surface damage, and achieved the goal of improving land productivity. The results presented provide the experimental evidence for the application of microhole subsoiling in cotton production.