Biosolids, Yield, Organic amendments in SOil. research to mitigate LeachIng and Denitrification: BYOSOLID

在Rothamsted的工作强烈表明，通过向土壤中添加有机物质，作物产量可以得到改善，而不是对修正物所含营养素的任何反应。其机制似乎是，土壤生物以改良剂为食，改善了土壤结构，从而使植物更容易生长并找到水和养分。在作物产量受到春季干旱或冬季潮湿影响的年份，种植在改良土壤中的作物表现特别好。目前，Rothamsted正在开展工作，以更好地了解这些观察背后的机制。该项目旨在将这一知识扩展到惠益的持续时间：在增加一项修正案之后多少年仍然可以看到产生的惠益，这些惠益可能有多大？有许多材料是或可以添加到土壤中，并应以这种方式增加产量：粪肥，堆肥，厌氧消化（AD），生物固体。在陆地上回收这些材料是有意义的，因为它们都以这样或那样的方式来自农业。但是，有与其使用相关的规定。欧盟法规限制含氮和磷的材料在硝酸盐脆弱区的应用，如果一种材料被定义为“废物”（其中一些是），那么许可证问题就变成了处置而不是回收问题。目前在Rothamsted的项目的目标是为农民提供使用有机添加物提高作物产量的指导方针。由于这些材料有污染环境的危险，管理机构有可能拒绝允许使用有机添加物或比目前更严格地限制其使用。该项目旨在不仅量化直接应用修正的氮排放风险，而且量化应用后几年的残留释放。该项目将审查目前正在接受修正的一些实验、在项目期间将停止接受修正的实验以及过去接受过修正但在过去10至15年期间停止的实验中的氮排放量。在所有情况下，我们知道我们可以找到地块，并有土地管理的记录，因为修正案。因此，我们希望能够建立从土地的养分流失的知识，最后收到0至15年前的修正案对一系列土壤类型的几种不同的修正案。将使用计算机模拟模型通过插值填补空白。这种全面的研究应有助于减少限制将有机材料回收到土地上的风险，或提供客观证据支持其有益使用或禁止任何限制的程度。肥料氮在盈亏平衡比（BER）下施用最经济-其中多施用一次肥料增量只会多支付一次产量增量。有机修订在Rothamsted似乎改变了作物的反应，以增加氮，因此在BER的N和产量的预期。修正的益处将以BER相对于产量和施用的肥料N的位置的变化以及肥料成本和产品价值来表示。APW一直在与安格利安水务公司就这个项目和HGCA联系，这两个公司都可能是主要受益者。PW还与堆肥行业讨论了潜在的结果。

Work at Rothamsted strongly suggests that by adding organic matter to soil, crop yields can be improved over and above any response to the nutrients that the amendments contain. The mechanism appears to be that soil organisms feeding off the amendments improve soil structure and thus allow plants to establish and find water and nutrients more easily. Crops grown in amended soils do especially well in years when crop yields are impacted by dry springs or wet winters. Work is underway at Rothamsted to better understand the mechanisms behind these observations. This project seeks to extend this knowledge to the duration of the benefit: how many years after an amendment has been added can the benefits to yield still be seen and how great might these be? There are many materials that are or could be added to soil and which ought to increase yields in this way: manure, compost, anaerobic digestate (AD), biosolids. Recycling these materials on land makes sense since they are all derived from agriculture in one way or another. However, there are regulations associated with their use. EU regulations restrict applications of materials containing N and P in Nitrate Vulnerable Zones and if a material is defined as a 'waste' (and some of these are) then the licensing issue becomes one of disposal rather than recycling. Current projects at Rothamsted have as their aims to produce guidelines to farmers on the use of organic amendments to improve crop yields. Because of the risk of environmental pollution from these materials there is a risk that regulatory agencies might refuse to permit the use of organic amendments or restrict their use still more than at present. This project aims to quantify not only the risk of N emissions from the direct application of amendments but also the residual release in the years subsequent to application. The project will examine emissions of N in a number of experiments currently receiving amendments, experiments that will cease to receive amendments during the course of the project and experiments which received amendments historically but which ceased during the last 10 to 15 years. In all cases, we know we can find the plots and have records of land management since amendment. Thus we expect to be able to build up knowledge of the loss of nutrients from land that last received amendment between 0 and 15 years ago on a range of soil types for several different kinds of amendment. Gaps will be filled by interpolation using computer simulation models. Such a comprehensive study should help mitigate the risks of restrictions being placed on the recycling of organic materials to land or provide objective evidence in support of their beneficial use or proscribe the extent of any restriction. Fertiliser N is most economically applied at the Break-Even Ratio (BER) - where application of one more increment of fertiliser only just pays for one more increment in yield. Organic amendments at Rothamsted appear to change the response of crops to added N and hence the N at BER and the amount of yield expected. Benefits from amendments will be expressed in terms of the change in position of the BER relative to yield and fertiliser N applied and in terms of the cost of fertiliser and the value of product. APW has been in touch with Anglian Water about this project and with HGCA, both of whom could be major beneficiaries. PW has also talked to the composting industry about the potential results.