农牧交错带不同间套作模式的土地生产力

    Productivity of strip intercropping systems in agro-pastoral ecotone

    • 摘要: 农牧交错带不同带状间套作不但是一种高产高效的生产技术,而且还是一种冬春季节防风固沙的生态保护措施。研究间套作对作物干物质积累过程和产量的影响,对于合理利用间套作技术提高土地生产力和改善生态环境有重要意义。该研究从2009年到2011年在内蒙古武川县进行大田试验,通过地上部干物质质量随大于0℃有效积温增长的指数线性(expolinear)关系对不同作物间作和单作的地上部干物质增长动态进行拟合,量化了间作模式下作物的生长速率的变化和生长与发育延缓的程度。采用土地当量比(land equivalent ratio,LER)研究了农牧交错带几种典型间作模式的土地生产力。结果表明: 向日葵/马铃薯、莜麦/马铃薯和莜麦/豆类大带宽(2 m:2 m带宽)间作具有显著的产量优势,基于经济产量的土地当量比LER分别为1.12、1.09和1.05,说明间作能提高土地生产力5%~12%。窄带宽模式(1 m:1 m带宽)间作优势小于大带宽模式,而且年际间的变幅较大。间作显著提高了向日葵收获指数,对其他作物收获指数的影响不显著。间作中高秆作物如莜麦在莜麦和豆类的间作中具有显著的边行优势。间作和单作相比,显著降低了作物最大生长速率(cm);但相对生长速率rm和单作的差异不显著;在间作中,矮秆作物(马铃薯和箭舌豌豆)的生长进程都有不同程度的延缓,到达冠层最大盖度时所需的有效积温比单作多117~387 ℃·d,考虑到试验区作物生长季内的日平均温度为15℃左右,这2种间作作物的生长延缓了约8~26d。总体来讲,农牧交错带的这几种典型带状间作种植模式都具有一定的间作产量优势和更高的经济效益,特别是大带宽间作模式,间作优势较为明显,而且还能降低农业生产的气候和市场风险。

       

      Abstract: Abstract: Strip intercropping system is not only a technique that achieves high productivity but also an important practice to protect winter and spring wind erosion in Agro-pastoral ecotone. Dry matter accumulation process and yield advantage of intercropping are vital indicators for exploration of intercropping performance and assessing the environmental benefit. This study is aiming to quantify crop growth, yield and land productivity in typical intercropping systems in agro-pastoral ecotone. An expolinear relationship between biomass growth and heat sum of above 0 ℃ temperature was fitted for different crops in the inter- and mono-cropping systems. The regression parameters were used to quantify the delay of crop growth in the intercropping. Land equivalent ratio (LER) was used to explain land productivity and over-yielding of the intercropping systems. The main results showed that sunflower/potato, oats/potato and oats/bean strip intercropping systems with wider width of strips (e.g. 2m:2m intercropping) significantly increased land productivity with yield land equivalent ratio (LER) of 1.12, 1.09 and 1.05, respectively, which means 5 % to 12 % of the land productivity increasing. Intercropping yield advantages were significantly higher in the wider strip intercropping systems than that with narrower ones (1 m:1 m intercropping), and had a less yearly variation. The harvest index (HI) of sunflower was significantly increased in intercropping, while that for other crops were significantly changed. A border row effect was clearly found in the oat based intercropping systems. The border rowers had a significantly higher yield compare to middle rows in the intercrops and sole oats. Strip intercropping decreased the maximum growth rate cm, while the relative growth rate rm stayed as the same as the monoculture. The growth delay of crops in the intercrops was quantified by using the parameter tb, which indicated the thermal time requirement at the time of reaching maximum canopy cover. The growth of five species in the intercropping systems, e.g. sunflower, potato, oats, faba bean and vetch, were delayed 117 to 387 degree days compared to that of monocultures, which resulted 8-26 d of growth delay when we took the daily average temperature (15℃) into accounts. All in all, Strip intercropping systems not only have over-yielding effects and higher economic benefits, especially in intercropping systems with wider strips, but also reduce the agricultural risks in the agro-pastoral ecotone climatically and economically.

       

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