SoilBioHedge: harnessing hedgerow soil biodiversity for restoration of arable soil quality and resilience to climatic extremes and land use changes

地球表面只有30%是陆地，只有9%是耕种的，未来扩张的空间很小。在大约7800千米(至0.5米)的表土中，从土壤向农作物提供的水和养分目前维持着70亿人的生计。这种土壤资源是可耕作农业的重要基础，粮食、纤维和生物燃料的植物生产最终依赖于整个全球经济。我们如何管理这种重要的、维持生命的资源，将决定生命的质量和地球对子孙后代的承载能力。SoilBioHedge解决了土壤安全的中心问题：持续的常规耕作耗尽了土壤有机质，退化了土壤结构，减少了排水和持水能力，并通过降低对洪水和干旱条件的适应能力增加了土壤和作物对气候胁迫影响的敏感性。我们将检验我们的中心假设：与未连接到农田边缘的Leys相比，播种到农田中的草三叶草能够使关键的生态工程师(蚯蚓和菌根真菌)重新聚集在农田中，恢复和改善土壤质量。我们将首次确定从树篱下的生物多样性避难所到通过草三叶草的耕地在恢复功能性生物多样性方面的重要性。我们将把土壤质量量化为土壤-生物相互作用的功能效益：土壤有机质、水稳定性大团聚体、持水能力、入渗率、抗旱性和抗洪性，以及由此产生的作物产量。我们将量化生态系统工程师(草三叶根、AM真菌和蚯蚓)和土壤功能与土地利用和管理变化协同发展的业务时间和空间尺度。我们将通过结合代谢组学和元基因组学分析来改变对土壤结构动力学的机械理解，跟踪3个生长季节的土壤团聚体形成。我们的研究设计包括三个嵌套的观察尺度。1)在利兹美国农场进行了树篱到农田的试验，以量化土壤功能和生物多样性的时空变化，这些变化是由断开或连接到农田边缘的耕地转化带引起的，并在2012年整个农田转为耕地，以及使用常规耕作与最少耕作条带和2009年转为农田的农田进行的农田到耕地的转化。整体式盆栽研究将使用从试验田移走的草坪块，用除草剂处理，并直接用小麦播种。我们将比较在模拟干旱和过量降雨导致洪水的情况下，在接近环境条件下保持的田间和整体作物产量。结果将量化土壤质量、作物和土壤有机体的弹性以及对这些压力的作用。2)景观尺度的绿篱-田间样带将在2个不同的时间尺度上量化长期耕地和成对退耕还田的土壤功能变化。我们将利用我们的&gt；100农场网络，提供一系列土壤类型和管理(常规、有机和最少耕作)。3)田间-景观尺度数学模型，建立农田-景观尺度土壤质量变化的综合预测时空模型，包括绿篱和农田边缘生物多样性扩散到耕地的作用，这是涉及土地利用和管理变化的结果。我们将通过我们的实验和景观尺度样带观测的根系、AM和蚯蚓的协同作用，将对土壤聚集和碳积累的机理理解与现有的农村调查数据和国家数字土壤地图相结合，以实现对可持续土壤管理政策和实践的理解的阶段性转变。

Only 30% of Earth's surface is land, only 9% is cultivated, and there is little scope for future expansion. The supply of water and nutrients from soil to crops in approximately 7800 km3 of topsoil (to 0.5 m) currently sustains 7 billion humans. This soil resource is the essential foundation of arable farming on which plant production for food, fiber and biofuels, and ultimately the entire global economy depends. How we manage this vital, life sustaining, resource will determine the quality of life and Earth's carrying capacity for future generations. SoilBioHedge addresses the central problem for soil security: continuous conventional arable cultivation depletes soil organic matter, degrades soil structure, reduces water drainage and water holding capacity, and increases the susceptibility of soil and crops to the impacts of climatic stress through decreased resilience to flood and drought conditions.We will test our central hypothesis: grass-clover leys sown into arable fields and connected to hedgerows and unploughed grassy margins enable key ecosystem-engineers (earthworms and mycorrhizal fungi) to recolonize the fields, restoring and improving soil quality compared to leys unconnected to field margins. We will determine for the first time the importance of connectivity from biodiversity refugia under hedgerows to arable fields via grass-clover leys in restoring functional biodiversity. We will quantify soil quality as functional benefits from soil-organism interactions: increases in soil organic matter, water-stable macroaggregates, water holding capacity, infiltration rates, drought and flood resilience, and resulting crop yields. We will quantify the operational temporal and spatial scales for ecosystem engineers (grass-clover roots, AM fungi, and earthworms) and soil functions to synergistically develop with land use and management change. We will transform mechanistic understanding of soil structure dynamics by combined metabolomics and metagenomic analyses tracking soil aggregate formation over 3 growing seasons. Our research design includes three nested scales of observation. 1) Hedge-to-Field Experiments at Leeds U. farm to quantify spatial/temporal changes in soil functions and biodiversity, arising from arable-to-ley conversion strips that are disconnected or connected to the field margin, and across a whole field converted to arable in 2012, and ley-to-arable conversion using conventional vs. minimal tillage strips and a field that converted to ley in 2009. Monolith mesocosm studies will use turf blocks removed from the experimental plots, treated with herbicide and direct drilled with wheat. We will compare crop yields between the field and monoliths maintained at near-ambient conditions, under simulated drought and excess rainfall causing flooding. The results will quantify soil quality and the resilience of the crop and soil organisms and functions to these stresses. 2) Landscape-Scale Hedge-to-Field Transects will quantify soil functional changes on long-term arable fields and pairs of arable fields converted to ley over 2 differing time scales. We will utilize our network of >100 farms that provide a range of soil types, and management (conventional, organic, and minimal tillage). 3) Field-to-Landscape Scale mathematical modelling to establish an integrative and predictive spatiotemporal model of soil quality change at field-to-landscape-scale, including the role of dispersal of hedgerow and field margin biodiversity into arable land resulting from land use and management change involving leys. We will integrate mechanistic understanding of soil aggregation and carbon accumulation through the synergistic actions of roots, AM, and earthworms from our experiments and landscape-scale transect observations with existing Countryside Survey data and national digital soil map, to deliver a step-change in understanding for sustainable soil management policy and practice.