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Maize crops shown to improve wheat yields, by boosting soil microbes
Farmers have long known that it's a good idea to rotate crops, and that concept is now getting a new spin. A Swiss study indicates that wheat yields are boosted when those crops are planted in fields previously used to grow maize, which altered the soil's microbiome.
As maize plants grow, their roots release chemicals known as benzoxazinoids. Deposited into the soil, these chemicals in turn affect what types of beneficial bacteria and fungi thrive there. Even after the plants have been harvested, the microbes remain in the soil.
In previous studies conducted at the University of Bern, lab tests showed that when wheat plants were grown in soil previously used to grow maize, they grew better than control plants. Led by professors Matthias Erb and Klaus Schläppi, a team of scientists from the university recently set out to see if the same effect would occur in a real-world agricultural setting.
In order to do so, they grew two types in maize in test plots – one was normal maize, while the other had been altered to not produce benzoxazinoids. After those crops had been harvested, three types of winter wheat were planted and grown in the same plots.
Over a two-year period, it was found that wheat grown in the benzoxazinoid-boosted soil had a 4% better yield. As an added bonus, the plants were less infested by pests. Although more research needs to be conducted, it is hoped that the findings could ultimately lead to reduced use of fertilizers and pesticides.
"A yield increase of 4% may not sound spectacular, but it is still significant considering how challenging it has become to enhance wheat yields without additional inputs," said Erb. "Whether effects of this kind actually make a significant difference for overall agricultural productivity and sustainability remains to be seen, however, as yield also depends on many other factors."
注释：
maize: n
表示"玉米"，如：Maize is widely planted in the America. 玉米在美洲广泛种植。
Benzoxazinoids: n
表示"苯并噁嗪,一类广泛存在于玉米、小麦等禾本科作物中的次生代谢物,也是该类作物根系分泌物中含量最高的次生代谢物,对多种病虫害具有广谱抗性。"，如：Research development on benzoxazinoids; 苯并噁唑嗪酮类化合物的研究进展
中文简要说明：
农民们早就知道轮耕作物是个好主意，现在这个概念有了新的发展。瑞士的一项研究表明，玉米是相当不错的轮耕作物，因为它留下的土壤的微生物组，很适合小麦，当小麦种植在先前种植玉米的田地中时，小麦产量有明显增加。
新阿特拉斯(New Altas)报导，瑞士伯尔尼大学(University of Bern)的艾尔布（Matthias Erb）教授与施拉比（Klaus Schläppi）教授的科学团队发现，玉米在生长过程中，其根部会释放出称为苯并恶嗪类化合物(benzoxazinoids)的化学物质，它们沉积到土壤中，会促进有益细菌和真菌在土壤中的良性增加。即使玉米在收获以后，有益的微生物群仍然留在土壤中。
实验室测试表明，这些受到苯并恶嗪类化合物滋养的土地，对小麦相当有益。当小麦种到这些土壤以后，它们成长的情况比对照组来的更好。
在完成实验室条件的测试后，科学团队就到真正的农田中再重复实验，他们在试验田中种植了两种类型的玉米，一种是会分泌苯并恶嗪的普通玉米，另一种经过基因修改，不产生苯并恶嗪类化合物的实验玉米。经过一次收成之后，在同一块土地上种植3种冬小麦。
在两年的时间的冬小麦种植期间，科学家发现，曾经种过普通玉米，含有苯并恶嗪类化合物的土壤，所收获的小麦产量提高了 4%，而且这些小麦很少受到害虫的侵扰。
事实上，科学家颇早就发现苯并恶嗪是一种天然的驱虫剂，对欧洲玉米螟( Ostrinia nubilalis ) 幼虫、甜菜夜蛾 ( Spodoptera exigua )、玉米叶蚜 ( Rhopalosiphum maidis )等其他害虫，都有天然防御功能。尽管还需要进行更多研究，但希望这些发现，也有助于减少化肥和农药的使用。
艾尔布教授表示：「产量增加 4%， 听起来并不吸引人，但考虑到在不增加额外投资的情况下，就能提高小麦产量是相当划算的。」
尤其重要的是，鉴于「黄小玉」(黄豆、小麦、玉米)是世界最重要的粮食，黄豆的固氮效果已是常识，如今玉米也发现改良土壤，减少病虫害的作用，这意味着3种作物具有互补与轮耕的效果，对农业规划者是相当重要的信息。
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