دانلود رایگان مقاله اثرات اصلاح تراکم خاک و گرده افشانی حشرات تناوب زراعی

Abstract

Pollination and biological nitrogen fixation are key ecosystem services, but their contribution to agricultural production might be influenced by simplified crop rotation and soil compaction, two factors known to limit yield. In a greenhouse experiment, we investigated the combined effect of crop rotation, soil compaction, and insect pollination on yield formation and on the contribution of biological fixation to nitrogen acquisition of faba bean. Seed yield was reduced under high soil compaction, and under ley rotation management and it was enhanced by insect pollination. For plants grown in soil from the ley rotation, insect pollination increased individual seed weight by 50% suggesting a contribution to seed quality by pollination for crop grown in soils where nutrients are limiting yield. Crop monoculture and high soil compaction interactively reduced the contribution of nitrogen fixation by 30%, suggesting that soil compaction exacerbates the negative effect of monoculture on nitrogen fixation. Overall the results revealed that interactive effects of management factors do affect nutrient acquisition. We provide evidence that reduced soil quality affect the capacity of legumes to deliver key ecosystem services to the agroecosystem.

Discussion

Management factors under intensive agriculture have been associated with yield decline and stagnation (Foley et al. 2005). We have demonstrated that plant responses to these factors can affect pollination benefits on seed size, but this did not affect the seed yield. We showed that combination of soil management affected the contribution of BNF to N acquired by the plant but, again, this effect was not reflected at the seed yield level. Insect pollination contributed 38.1% to seed yield in our study, which is in accordance with a general estimate for the contribution of pollination of 36% to yield of faba bean (Free 1993). Previous exclusion experiments have found that faba bean produced fewer pods, fewer seeds per pod, and lower yield in absence of pollination (Poulsen 1975; Free & Williams 1976; Stoddard & Bond 1987; Suso, Moreno, Mondragao-Rodrigues, & Cubero 1996), and our results largely confirm this. We found no interact