{"title":"地中海型种植系统中热带豆科夏季覆盖作物对氮的潜在贡献","authors":"S. Parvin, J. Condon, Terry J. Rose","doi":"10.3390/nitrogen3040038","DOIUrl":null,"url":null,"abstract":"Legume cover crops in temperate cropping systems can fix substantial amounts of nitrogen (N) and reduce N fertiliser requirements for subsequent crops. However, little is known about potential biological N2 fixation by summer cover crop legumes in the short summer fallow in Mediterranean-type cropping systems. Six legume species (balansa clover, barrel medic, mung bean, sunn hemp, lablab and cowpea) were grown for 8–9 weeks in the field in semi-arid southern Australia during the summer fallow, and in a glasshouse experiment, to estimate N2 fixation using the 15N natural abundance method. Cowpea, sunn hemp and lablab produced 1.2–3.0 t ha−1 biomass in the field while balansa clover and barrel medic produced < 1.0 t ha−1. The percent of N derived from the atmosphere (%Ndfa) in the field ranged from 39% in barrel medic to 73% in sunn hemp, but only 15% (balansa clover) to 33% (sunn hemp) in the glasshouse experiment, likely due to higher soil mineral N availability in the glasshouse study. Biological N2 fixation of cowpea and sunn hemp in the field was 46–55 kg N ha−1, while N2 fixation in lablab and mung bean was lower (around 26 kg N ha−1). The N2 fixation in cowpea and sunn hemp of around 50 kg N ha−1 with supplementary irrigation in the field trial likely represents the upper limit of N contributions in the field in typically hot, dry summer conditions in Mediterranean-type climates. Given that any increase in summer cover crop biomass will have implications for water balances and subsequent cash crop growth, maximising N benefits of legume cover crops will rely on increasing the %Ndfa through improved rhizobium strains or inoculation technologies. This study provides the first known estimates of biological N2 fixation by legume cover crops in the summer fallow period in cropping systems in Mediterranean-type environments, providing a benchmark for further studies.","PeriodicalId":19365,"journal":{"name":"Nitrogen","volume":"5 2 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":"{\"title\":\"Potential Nitrogen Contributions by Tropical Legume Summer Cover Crops in Mediterranean-Type Cropping Systems\",\"authors\":\"S. Parvin, J. Condon, Terry J. Rose\",\"doi\":\"10.3390/nitrogen3040038\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Legume cover crops in temperate cropping systems can fix substantial amounts of nitrogen (N) and reduce N fertiliser requirements for subsequent crops. However, little is known about potential biological N2 fixation by summer cover crop legumes in the short summer fallow in Mediterranean-type cropping systems. Six legume species (balansa clover, barrel medic, mung bean, sunn hemp, lablab and cowpea) were grown for 8–9 weeks in the field in semi-arid southern Australia during the summer fallow, and in a glasshouse experiment, to estimate N2 fixation using the 15N natural abundance method. Cowpea, sunn hemp and lablab produced 1.2–3.0 t ha−1 biomass in the field while balansa clover and barrel medic produced < 1.0 t ha−1. The percent of N derived from the atmosphere (%Ndfa) in the field ranged from 39% in barrel medic to 73% in sunn hemp, but only 15% (balansa clover) to 33% (sunn hemp) in the glasshouse experiment, likely due to higher soil mineral N availability in the glasshouse study. Biological N2 fixation of cowpea and sunn hemp in the field was 46–55 kg N ha−1, while N2 fixation in lablab and mung bean was lower (around 26 kg N ha−1). The N2 fixation in cowpea and sunn hemp of around 50 kg N ha−1 with supplementary irrigation in the field trial likely represents the upper limit of N contributions in the field in typically hot, dry summer conditions in Mediterranean-type climates. Given that any increase in summer cover crop biomass will have implications for water balances and subsequent cash crop growth, maximising N benefits of legume cover crops will rely on increasing the %Ndfa through improved rhizobium strains or inoculation technologies. This study provides the first known estimates of biological N2 fixation by legume cover crops in the summer fallow period in cropping systems in Mediterranean-type environments, providing a benchmark for further studies.\",\"PeriodicalId\":19365,\"journal\":{\"name\":\"Nitrogen\",\"volume\":\"5 2 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2022-10-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"2\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Nitrogen\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.3390/nitrogen3040038\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Nitrogen","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3390/nitrogen3040038","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 2
摘要
在温带种植系统中,豆科覆盖作物可以固定大量的氮,并减少后续作物对氮肥的需求。然而,在地中海型种植系统中,夏季覆盖作物豆科植物在夏季短暂休耕中潜在的生物固氮作用尚不清楚。采用15N自然丰度法对6种豆科植物(balansa clover, barrel medic,绿豆,sunhemp, lablab和豇豆)进行了8-9周的夏季休耕,并在温室试验中进行了固氮估算。豇豆、太阳麻和lablab在田间的生物量为1.2-3.0 t ha - 1,而balansa clover和桶草的生物量< 1.0 t ha - 1。田间从大气中获得的氮的百分比(%Ndfa)在桶草中为39%,在太阳麻中为73%,但在温室试验中仅为15% (balansa clover)至33%(太阳麻),可能是由于温室研究中土壤矿质氮的有效性较高。豇豆和麻在田间的生物固氮量为46 ~ 55 kg N ha - 1,而在实验室和绿豆的固氮量较低(约26 kg N ha - 1)。在田间试验中,豇豆和大麻的固氮量约为50 kg N ha - 1,并辅以灌溉,这可能代表了在地中海型气候典型炎热干燥的夏季条件下,田间氮贡献的上限。鉴于夏季覆盖作物生物量的任何增加都将对水分平衡和随后的经济作物生长产生影响,豆科覆盖作物氮效益的最大化将依赖于通过改进根瘤菌菌株或接种技术来增加Ndfa的百分比。本研究首次估算了地中海型环境中豆科覆盖作物在夏季休耕期的生物固氮作用,为进一步研究提供了基准。
Potential Nitrogen Contributions by Tropical Legume Summer Cover Crops in Mediterranean-Type Cropping Systems
Legume cover crops in temperate cropping systems can fix substantial amounts of nitrogen (N) and reduce N fertiliser requirements for subsequent crops. However, little is known about potential biological N2 fixation by summer cover crop legumes in the short summer fallow in Mediterranean-type cropping systems. Six legume species (balansa clover, barrel medic, mung bean, sunn hemp, lablab and cowpea) were grown for 8–9 weeks in the field in semi-arid southern Australia during the summer fallow, and in a glasshouse experiment, to estimate N2 fixation using the 15N natural abundance method. Cowpea, sunn hemp and lablab produced 1.2–3.0 t ha−1 biomass in the field while balansa clover and barrel medic produced < 1.0 t ha−1. The percent of N derived from the atmosphere (%Ndfa) in the field ranged from 39% in barrel medic to 73% in sunn hemp, but only 15% (balansa clover) to 33% (sunn hemp) in the glasshouse experiment, likely due to higher soil mineral N availability in the glasshouse study. Biological N2 fixation of cowpea and sunn hemp in the field was 46–55 kg N ha−1, while N2 fixation in lablab and mung bean was lower (around 26 kg N ha−1). The N2 fixation in cowpea and sunn hemp of around 50 kg N ha−1 with supplementary irrigation in the field trial likely represents the upper limit of N contributions in the field in typically hot, dry summer conditions in Mediterranean-type climates. Given that any increase in summer cover crop biomass will have implications for water balances and subsequent cash crop growth, maximising N benefits of legume cover crops will rely on increasing the %Ndfa through improved rhizobium strains or inoculation technologies. This study provides the first known estimates of biological N2 fixation by legume cover crops in the summer fallow period in cropping systems in Mediterranean-type environments, providing a benchmark for further studies.