Capstaff Nicola M, Domoney Claire, Miller Anthony J
Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
Plant Methods. 2021 Jan 30;17(1):11. doi: 10.1186/s13007-021-00713-w.
Management regime can hugely influence the efficiency of crop production but measuring real-time below-ground responses is difficult. The combination of fertiliser application and mowing or grazing may have a major impact on roots and on the soil nutrient profile and leaching.
A novel approach was developed using low-cost ion-selective sensors to track nitrate (NO) movement through soil column profiles sown with the forage crops, Lolium perenne and Medicago sativa. Applications of fertiliser, defoliation of crops and intercropping of the grass and the legume were tested. Sensor measurements were compared with conventional testing of lysimeter and leachate samples. There was little leaching of NO through soil profiles with current management practices, as monitored by both methods. After defoliation, the measurements detected a striking increase in soil NO in the middle of the column where the greatest density of roots was found. This phenomenon was not detected when no NO was applied, and when there was no defoliation, or during intercropping with Medicago.
Mowing or grazing may increase rhizodeposition of carbon that stimulates soil mineralization to release NO that is acquired by roots without leaching from the profile. The soil columns and sensors provided a dynamic insight into rhizosphere responses to changes in above-ground management practices.
管理制度会极大地影响作物生产效率，但测量地下实时响应却很困难。施肥与刈割或放牧相结合可能会对根系、土壤养分状况及淋溶产生重大影响。
开发了一种新方法，利用低成本离子选择性传感器追踪硝酸盐（NO）在播种了牧草黑麦草和苜蓿的土壤柱剖面中的移动情况。对施肥、作物刈割以及草与豆科植物间作进行了测试。将传感器测量结果与蒸渗仪和渗滤液样品的传统测试结果进行了比较。两种方法监测结果均显示，在当前管理措施下，土壤剖面中NO的淋溶很少。刈割后，测量发现柱体中部土壤NO显著增加，该部位根系密度最大。未施加NO、未进行刈割或与苜蓿间作时，未检测到这种现象。
刈割或放牧可能会增加碳的根际沉积，从而刺激土壤矿化释放出NO，这些NO被根系吸收，不会从剖面中淋溶出去。土壤柱和传感器为根际对地上管理措施变化的响应提供了动态见解。
