Antecedent effects of catch crops upon the cycling of phosphorus in agro-ecosystems and scavenging of plant-fixed phosphorus by the soil microbiome

所有植物的生长都需要磷(P)。现代农业依赖于磷肥的定期投入，在作物收割后补充土壤。土壤中很大一部分磷是强结合的，对植物有效无效。捕获作物——在没有植被覆盖的情况下种植以减少主要作物之间的养分损失的植物品种——被成功地用于减少土壤中的氮(N)淋失，在植物组织中“捕获”矿化的氮，这些氮在植被分解后释放出来。关于捕获作物在限制磷损失和向主要作物提供磷方面的有效性，人们知之甚少。一旦被捕获，衰老作物中的磷将以核酸或ATP的形式存在，但以植酸盐的形式存在的比例更大，植酸盐是一种复杂的储存分子，一旦进入土壤，植物就无法获得。然而，植酸盐可以被真菌和细菌吸收。为了使这些储存物可供作物使用，需要微生物酶（各种植酸酶和磷酸酶）来水解植酸盐。如果要开发捕获作物以提高磷的利用效率，一个重要的考虑因素是前代作物对支持和调节土壤微生物组的植酸水解成员及其对磷的动员的影响，使其可用于主要作物。该项目将探讨与目前通常用作捕获和覆盖作物的植物有关的这种现象，并考虑在这方面可能具有增强能力的新物种。目的：(i)确定作为捕获作物种植时具有从土壤中积累磷的最佳特性的候选植物物种；（ii）确定这些物种支持土壤微生物群的能力，提高其水解植酸盐的能力；（iii）探索这些物种作为改善土壤磷管理和供应的实际手段的潜力，作为生产系统中的新型捕捞作物。

All plants require phosphorus (P) for growth. Modern agriculture depends on regular inputs of phosphate fertilizer, replenishing soil following crop removal. Large proportions of P in soils are strongly bound, effectively unavailable to plants. Catch crops - plant varieties grown to reduce nutrient losses between main crops when there is otherwise no vegetation cover - are successfully used to reduce nitrogen (N) leaching from soils, 'trapping' mineralised N in plant tissue which is released following vegetation decomposition. Much less is known regarding the effectiveness of catch crops in limiting P losses and provisioning P to main crops. Once captured, P in senescent catch crops will be present as nucleic acids or ATP, but with a greater proportion in the form of phytate, a complex storage molecule which once in soil is inaccessible to plants. However, phytate can be assimilated by fungi and bacteria. For these stores to become available to crops, microbial enzymes (various phytases and phosphatases) are required to hydrolyse phytate. An important consideration if catch crops are to be developed to increase P use efficiency is the effect antecedent crops have on supporting and conditioning the phytate-hydrolysing members of the soil microbiome and their mobilisation of P to render it available to main crops. This project will explore such phenomena in relation to plants currently commonly used as catch and cover crops, and consider novel species which may have enhanced capabilities in this respect.Aims: (i) identify candidate plant species with optimal properties to accumulate P from soils when grown as catch crops; (ii) determine the ability of such species to support soil microbiomes with increased capacities to hydrolyse phytate; (iii) explore the potential for such species to be used as a practical means to improve soil phosphorus management and supply, as novel catch crops in production systems.