我們低估了堆肥對碳的捕獲能力

19年的研究表明，我們低估了堆肥能促進碳捕獲的程度

It's no secret that organic farmers believe in compost, but just what role compost plays in soil's ability to store carbon - and keep it out of the atmosphere, where it contributes to climate change - has been less clear.

有機農(nóng)民相信堆肥已經(jīng)不是什么秘密了，但是堆肥在土壤儲存碳的能力中扮演著怎樣的角色——并且不讓碳進入大氣層，因為這是造成氣候變化的原因——一直不太清楚。

A recent study out of the University of California, Davis suggests that compost plays a larger role than once thought in building soil carbon.

加州大學(xué)戴維斯分校(University of California, Davis)最近的一項研究表明，堆肥在土壤碳排放中發(fā)揮的作用比人們曾經(jīng)認(rèn)為的要大。

It also found that carbon levels fluctuate more in deeper soil than most evaluation methodologies tend to account for. In practical terms, the findings could mean compost has been undervalued by agricultural incentive programs, and that we've been measuring carbon levels in soil all wrong.

研究還發(fā)現(xiàn)，深層土壤中的碳含量波動比大多數(shù)評估方法所考慮的要大。在實際操作中，這些發(fā)現(xiàn)可能意味著堆肥被農(nóng)業(yè)激勵計劃低估了，我們一直在測量土壤中的碳水平都是錯誤的。

Nicole Tautges, co-author of the study, says it wasn't a surprise to find that compost is good at helping soil store carbon - it's where exactly it does this that was revealing.

這項研究的合著者Nicole Tautges說，發(fā)現(xiàn)堆肥在幫助土壤儲存碳方面很好并不令人驚訝，這正是堆肥的作用所在。

"The surprising piece was that it raised soil carbon between one and two meters deep. Because the big question is, 'How does the carbon get down there when we're only applying it in the top foot?'" adds Tautges, the chief cropping systems scientist at the UC Davis Agricultural Sustainability Institute.

“令人驚訝的是，它使土壤的碳含量增加了1到2米深。因為最大的問題是，‘當(dāng)我們只把碳涂在腳上的時候，碳是怎么落到腳上的?’”加州大學(xué)戴維斯農(nóng)業(yè)可持續(xù)研究所首席作物系統(tǒng)科學(xué)家陶茨補充道。

In the study, which was published this summer in the journal Global Change Biology and conducted at a long-term research site the university initiated in 1993, the researchers measured soil organic carbon at five different depths down to two meters over a period of 19 years.

這項研究于今年夏天發(fā)表在《全球變化生物學(xué)》(Global Change Biology)雜志上，并在該校1993年啟動的一個長期研究基地進行。在這項研究中，研究人員在19年間測量了5個不同深度至2米以下的土壤有機碳。

They compared the carbon levels across a number of different cropping systems - conventional, conventional with cover crops, and one that included the application of compost alongside cover crops.

他們比較了幾種不同種植系統(tǒng)的碳水平——傳統(tǒng)的、傳統(tǒng)的覆蓋作物，以及一種包括在覆蓋作物旁邊施用堆肥的種植系統(tǒng)。

Researchers found that systems using cover crops alone not only failed to store more carbon, they actually lost significant amounts of carbon in the soil below about a foot deep. The system that used both cover crops and compost, however, had significantly increased soil carbon content over the length of the study - about 0.7 percent annually.

研究人員發(fā)現(xiàn)，僅使用覆蓋作物的系統(tǒng)不僅不能儲存更多的碳，實際上還會在約一英尺深的土壤中損失大量的碳。然而，在整個研究過程中，覆蓋作物和堆肥的系統(tǒng)顯著增加了土壤的碳含量——大約每年增加0.7%。

That may sound like a small number, but it's enormous in the context of soil, where change is slow and gradual. The "4 per 1,000" initiative has called for a 0.4 percent increase in soil carbon annually around the globe as a way to combat climate change.

這聽起來可能是一個很小的數(shù)字，但在土壤變化緩慢而漸進的背景下，這個數(shù)字是巨大的。“千分之四”倡議呼吁全球每年增加0.4%的土壤碳，以應(yīng)對氣候變化。