农田机械碾压对土壤物理特性及玉米生长和产量的影响

Effects of mechanical compaction on soil physical properties, maize growth and yield in farmland

  • 摘要: 【目的】研究实际生产中大型农业机械碾压对土壤物理特性及玉米生长和产量的影响程度,为改善耕作措施、实现作物壮根高产和土壤的可持续生产提供依据。【方法】选取小麦—玉米两熟制中前茬小麦收获时节受谷物联合收割机反复碾压的地块(JS处理)和常规收割未经反复碾压地块(CK),以玉米品种登海605(DH605)和登海3号(DH3)为试验材料,测定并分析玉米播种前的土壤容重和含水量及玉米的农艺性状、光合特性、干物质积累与分配、果穗性状及产量等指标。【结果】JS处理地块0~50 cm土层土壤容重和土壤含水量均较CK增加,其中0~10和10~20 cm土层土壤容重均显著大于CK(P<0.05,下同),即大型农机反复碾压对土壤容重的影响主要集中在0~20 cm耕层。耕层土壤紧实进一步造成玉米根系发根数量减少,根干质量降低,根冠发育失调,茎、叶分化受阻,单株叶片数量和茎节数量减少,叶面积指数下降,株高降低,光合速率降低,干物质积累量减少,穗粒数和百粒质量下降。2个品种比较,DH3根系生长受紧实胁迫影响较大,根层数、根条数、根干质量、根冠比较CK分别显著减少17.9%、26.9%、45.2%和32.9%,而DH605分别下降0、14.4%、31.7%和12.7%,仅根干质量达到显著差异;JS处理下DH605的叶面积指数和穗位叶SPAD较CK分别显著降低36.9%和14.4%,穗位系数显著增加,茎粗、百粒质量显著降低;虽然DH3根系生长受紧实胁迫影响较大,JS处理下DH3的叶面积指数较CK显著降低21.8%,但穗位叶SPAD值、穗位系数、茎粗、百粒质量则与CK差异不显著(P>0.05),且干物质向叶片、籽粒的分配比例增加,最终减产幅度(20.8%)与DH605(24.4%)差异不大。【结论】当前生产中大型农机反复碾压造成的耕层土壤紧实现象已十分严重,使免耕直播的玉米生长受到明显抑制,产量显著降低;不同玉米品种对土壤紧实胁迫的响应存在差异,生产中可通过深松深耕、秸秆还田、选用抗土壤紧实品种等措施消减土壤紧实对作物生长的不良影响。

     

    Abstract: 【Objective】The effect of large-scale agricultural machinery compaction on soil physical characteristics, and the growth and yield of maize in practical production was studied to provide the basis for improving tillage measures, achieving strong roots and high yields of crops and sustainable production of soil.【Method】Recompacted plot(JS) by grain combine harvester and conventional harvest without recompacted plot(CK) at wheat harvest time were selected in wheat-corn double cropping system, and using maize varieties Denghai 605(DH605) and Denghai 3(DH3) as materials, bulk density and water content of soil before maize sowing and agronomic traits, photosynthetic characteristics, dry matter accumulation and distribution, ear traits and yield of maize were measured.【Result】The soil bulk density and water content in the 0-50 cm soil layer of JS treatment were both higher than that of CK, and the soil bulk density of 0-10 and 10-20 cm soil layers were significantly higher than that of CK(P<0.05, the same below). That was to say, the effect of repeated compaction by large agricultural machinery on the soil bulk density was mainly concentrated in the 0-20 cm arable layer. Arable layer soil compaction resulted in the decrease of maize root number and root dry weight, the developmental dysplasia of root and overground parts, blocked stem and leaf differentiation, and the decrease of leaves number and internodes per plant, the decline ofleaf area index, plant height, photosynthetic rate, dry matter accumulation, the decrease of grains number per ear and 100-grain weight, ultimately led to more than 20% reduction in yield. Compared with two cultivars, the root growth of DH3 was greatly affected by compaction stress. Compared with CK, the root layer number, root number, root dry weight and root-top ratio of DH3 under JS treatment were significantly reduced by 17.9%, 26.9%, 45.2% and 32.9%, respectively, while DH605 were decreased by 0, 14.4%, 31.7% and 12.7%, respectively, and only the root dry weight was significantly different. Compared with CK, leaf area index and SPAD of ear leaf of DH605 were significantly decreased by 36.9% and 14.4%, respectively, ear coefficient was significantly increased, stem diameter and 100-grain weight were significantly decreased under JS treatment. Although DH3 root growth were greatly influenced by compaction stress, leaf area index of DH3 was 21.8% lower than CK, and the SPAD of ear leaf, ear coefficient, stem diameter, 100-grain weight of DH3 under JS treatment were not significantly different with CK(P>0.05), and the proportion of dry matter allocated to leaves, and grains increased than CK under JS treatment. Eventually, the yield reduction(20.8%) was not greatly different with DH605(24.4%). 【Conclusion】The phenomenon of surface soil compaction caused by repeated rolling of large farm machines in current production has been very serious, which inhibits the growth of no-tillage direct seeding maize and significantly reduced the yield. Different maize varieties have different responses to soil compaction stress. In production, the adverse effects of soil compaction on crop growth can be reduced by deep loosening(ploughing), straw returning to the field, and selection of soil compaction resistant varieties.

     

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