Meta分析表明土壤覆盖可显著提高农作物产量和水氮利用效率

    《摘要》在全球范围内，农作物产量受水和养分的严重制约。土壤覆盖可以减少蒸发和改变土壤温度。然而，相关土壤覆盖的研究结果有时是相互矛盾的。覃伟、胡春胜、Oene Oenema关于土壤覆盖对小麦和玉米产量的影响---meta分析研究结果最近发表在自然《科学报告》。

    小麦和玉米占世界谷物产量的70％。但小麦和玉米产量受水分和养分供应的制约，尤其是在干旱和半干旱地区。即使有足够的水分和养分投入，由于水肥管理不善，小麦和玉米的水分和养分利用效率也很低，从而导致大量水肥损失。据预测，2050年全球粮食生产，包括小麦，玉米，要增加一倍，才能养活不断增长的世界人口。目前全球人口是70亿，预计在2050年将达90-100亿。这将急剧增加对于有限天然资源利用的压力，如土地，水和营养物质等资源。因此，在主要农作物系统中，特别是在雨养农业系统，迫切需要增加水分和养分利用效率。土壤秸秆或地膜覆盖可以成为有用的选项。但由于气候条件，土壤特性，作物种类，水氮投入的差异，这些因素都可能影响土壤覆盖的效果。

    最近，在一项中科院与瓦格宁根大学联合项目中，覃伟、胡春胜、Oene Oenema通过meta分析方法，发现土壤覆盖可以减少蒸发量，改变土壤的温度，从而影响作物产量。数据来自于19个国家进行的74个研究，其中包含1300多个产量和水肥投入数据。作者按：“我们的研究结果表明，与无覆盖进行比较，土壤覆盖显著增加产量，以及水氮利用效率（高达60％）。在增产增效方面，玉米比小麦效果强，地膜覆盖比秸秆覆盖效果强。有趣的是，地膜覆盖在低温地区效果更好，而秸秆覆盖则表现出相反的趋势。土壤覆盖的增产效果随着水投入增加趋于减小。土壤覆盖效果与土壤有机质含量没有显著关系。我们的结论是土壤覆盖能显著提高玉米和小麦产量以及水氮利用效率，特别是在干旱和低养分投入农业体系，从而有助于缩小理论产量与实际产量差。”

文章链接：http://www.nature.com/articles/srep16210

后记：

  过去几年来，我一直关注和研读科学网论文区里分享和推荐的文章（http://www.sciencenet.cn/earth/），受益良多！

    因为自己从事的研究属于农学土壤学领域，因此读的文章大多是农学方面的，主要是水肥管理，其他领域的文章也会研读。长期坚持一段时间后，发现对于快速阅读文献，学习科研写作等诸多方面，都很有收获和进步。最近自己的一篇文章有幸能发表在《科学报告》。其中的结果和meta分析方法，可供大家参考。

    这篇文章主要是通过meta研究方法，构建了全球小麦与玉米生产体系针对土壤秸秆覆盖及覆膜研究的大数据库，深入分析并定量化秸秆覆盖及覆膜对产量的贡献（高达60%），以及气候变化、土壤性状及有机质、以及作物类型对水氮利用效率和相互作用的影响。该研究于2015年11月20日发表于Scientific Reports《科学报告》，并得到瓦格宁根大学（瓦大）官方新闻网的报导。

该研究的结果以及分析方法等，期待能有机会和大家一起共同探讨和改进。其中包括数据库的建立、meta分析方法、R语言代码等等，都可以提供给大家参考。也欢迎大家与我联系并讨论实验设计、数据分析以及科研文章写作等方面的问题。我的email是weiqinwur@gmail.com。

瓦大报导的英文内容如下：

Soil mulching enhances yields and water and nitrogen use up to 60%  

(Highlight) Global crop yields are limited by water and nutrient availability. Soil mulching is expected to reduce evaporation and to modify soil temperature. However, reported effects of mulching are sometimes contradictory. Wei Qin, Chunsheng Hu and Oene Oenema published this week in Nature’s Scientific Reports a meta-analysis of the effects of mulching on wheat and maize.

Wheat and maize account for some 70% of the world’s cereal production. Their yields, however, are significantly limited by the availability of water and nutrients, especially in arid and semi-arid regions. In regions with sufficient water and nutrient input, the water and nutrient use efficiencies of wheat and maize are often low due to suboptimal management, which leads to large losses. Forecasts project that food production, including wheat and maize, will have to double in order to feed the growing world population, now 7 billion but expected to be 9 to 10 billion in 2050. This will increase the pressure on the use of our limited natural resources, such as land, water and nutrients. So there is an urgent need to increase water and nutrient use efficiencies in the major cropping systems, especially in rainfed agricultural systems. Mulching could be a useful option. But in the field, there are differences in climatic conditions, soil characteristics, crop species, and water and nitrogen input levels. This might influence the effects of mulching.

In a joint project, Wageningen University and the Chinese Academy of Sciences examined the effect of soil mulching with plastic or straw. Wei Qin, Chunsheng Hu and Oene Oenema found that it reduces evaporation, modifies soil temperature and thereby affects crop yields. They did a metaanalysis of the effects of mulching on wheat and maize, using 1310 yield observations from 74 studies conducted in 19 countries: “Our results indicate that mulching significantly increased yields, yield per unit water and yield per unit nitrogen by up to 60%, compared with no mulching.

Effects were larger for maize than wheat, and larger for plastic mulching than straw mulching. Interestingly, plastic mulching performed better at relatively low temperature while straw mulching showed the opposite trend. Effects of mulching also tended to decrease with increasing water input. Mulching effects were not related to soil organic matter content. We conclude that soil mulching can significantly increase maize and wheat yields, yield per unit water and yield per unit nitrogen, and thereby may contribute to closing the yield gap between attainable and actual yields, especially in dryland and low nutrient input agriculture.”

Link of the article: http://www.nature.com/articles/srep16210