Old world bluestems (Bothriochloa spp.) have been successfully introduced as grasses for livestock forage in the semiarid Texas High Plains. Questions remain, however, on effects of these grasses on soil resources. We...Old world bluestems (Bothriochloa spp.) have been successfully introduced as grasses for livestock forage in the semiarid Texas High Plains. Questions remain, however, on effects of these grasses on soil resources. We tested the hypothesis that differences in grass species produce differences in soil properties important to crop growth and useful in selecting the optimum species for the Southern High Plains of Texas. Three old world bluestem (Bothriochloa) species [C.E. Hubbard ‘Caucasian’, B. caucasica (Trin.);‘WW Spar’, B. ischaemum (L.) Keng.var ischaemum (Hack.);and S.T. Blake ‘WW-B Dahl’, B. bladhii (Retz)] were grown in a randomized complete block design, with three replications, for nine years on a clay loam soil near Lubbock, Texas. Soil samples were collected in the ninth year to determine soil texture, wet aggregate stability, bulk density (BD), soil organic carbon (SOC), particulate organic carbon (POC), and soil strength as measured by the cone pentrometer. The grass species differed in their above-ground biomass and below- ground root production. In the ninth year of production, Bothriochloa caucasica and B. bladhii produced about twice the above-ground biomass with about 25% fewer roots than B. ischaemum. Soils where B. caucasica was grown had the highest BD (1.36 Mg m–3) and B. ischaemum had the lowest (1.31 Mg m–3). The soil in which B. ischaemum was growing had a lower BD, greatest root biomass, organic matter content, and aggregate stability suggesting superior soil quality for agricultural production. The species B. bladhii, however, often exhibited soil properties that were similar to both other species tested. Since Bothriochloa bladhii had superior or similar soil properties for plant growth among the species tested and has been shown to be higher in forage quality, animal performance, and carrying capacity than the other species, it appears to be the best choice among these three species to optimize both animal performance and desirable soil properties.展开更多
植物生长及养分利用特征可揭示半干旱区植物对多变水肥环境条件的适应策略。在白羊草分蘖期设置2个供水条件(正常供水和干旱胁迫21天后复水)和2个磷添加水平(复水当日1 kg干土添加0,0.2 g P2O5),2周后测定其根冠生物量、根系形态以及氮...植物生长及养分利用特征可揭示半干旱区植物对多变水肥环境条件的适应策略。在白羊草分蘖期设置2个供水条件(正常供水和干旱胁迫21天后复水)和2个磷添加水平(复水当日1 kg干土添加0,0.2 g P2O5),2周后测定其根冠生物量、根系形态以及氮磷含量。结果表明,旱后复水条件下,磷添加后白羊草根冠生物量、总生物量和根冠比无显著变化,总根长和根表面积显著增加27.1%和24.1%,比根长和比根面积分别显著增加18.3%和15.9%,根系平均直径显著降低1.3%;白羊草地上部、根系和整株磷含量分别显著增加61.1%,35.8%和49.6%,磷累积量分别显著增加68.6%,52.0%和61.3%,氮磷比显著降低。除地上部氮累积量外,各水分和磷处理下白羊草地上部、根系和整株氮磷累积量与总根长和根表面积呈显著正相关关系。本研究表明,根长和根表面积增加是白羊草响应水肥环境条件改善的主要策略。展开更多
文摘Old world bluestems (Bothriochloa spp.) have been successfully introduced as grasses for livestock forage in the semiarid Texas High Plains. Questions remain, however, on effects of these grasses on soil resources. We tested the hypothesis that differences in grass species produce differences in soil properties important to crop growth and useful in selecting the optimum species for the Southern High Plains of Texas. Three old world bluestem (Bothriochloa) species [C.E. Hubbard ‘Caucasian’, B. caucasica (Trin.);‘WW Spar’, B. ischaemum (L.) Keng.var ischaemum (Hack.);and S.T. Blake ‘WW-B Dahl’, B. bladhii (Retz)] were grown in a randomized complete block design, with three replications, for nine years on a clay loam soil near Lubbock, Texas. Soil samples were collected in the ninth year to determine soil texture, wet aggregate stability, bulk density (BD), soil organic carbon (SOC), particulate organic carbon (POC), and soil strength as measured by the cone pentrometer. The grass species differed in their above-ground biomass and below- ground root production. In the ninth year of production, Bothriochloa caucasica and B. bladhii produced about twice the above-ground biomass with about 25% fewer roots than B. ischaemum. Soils where B. caucasica was grown had the highest BD (1.36 Mg m–3) and B. ischaemum had the lowest (1.31 Mg m–3). The soil in which B. ischaemum was growing had a lower BD, greatest root biomass, organic matter content, and aggregate stability suggesting superior soil quality for agricultural production. The species B. bladhii, however, often exhibited soil properties that were similar to both other species tested. Since Bothriochloa bladhii had superior or similar soil properties for plant growth among the species tested and has been shown to be higher in forage quality, animal performance, and carrying capacity than the other species, it appears to be the best choice among these three species to optimize both animal performance and desirable soil properties.
文摘植物生长及养分利用特征可揭示半干旱区植物对多变水肥环境条件的适应策略。在白羊草分蘖期设置2个供水条件(正常供水和干旱胁迫21天后复水)和2个磷添加水平(复水当日1 kg干土添加0,0.2 g P2O5),2周后测定其根冠生物量、根系形态以及氮磷含量。结果表明,旱后复水条件下,磷添加后白羊草根冠生物量、总生物量和根冠比无显著变化,总根长和根表面积显著增加27.1%和24.1%,比根长和比根面积分别显著增加18.3%和15.9%,根系平均直径显著降低1.3%;白羊草地上部、根系和整株磷含量分别显著增加61.1%,35.8%和49.6%,磷累积量分别显著增加68.6%,52.0%和61.3%,氮磷比显著降低。除地上部氮累积量外,各水分和磷处理下白羊草地上部、根系和整株氮磷累积量与总根长和根表面积呈显著正相关关系。本研究表明,根长和根表面积增加是白羊草响应水肥环境条件改善的主要策略。
