Muhandiram Nuwan P K, Humphreys Mike W, Fychan Rhun, Davies John W, Sanderson Ruth, Marley Christina L
Institute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Wales UK.
Food Energy Secur. 2020 Aug;9(3):e227. doi: 10.1002/fes3.227. Epub 2020 Jul 5.
The increasing frequency of droughts and floods on grasslands, due to climate change, increases the risk of soil compaction. Soil compaction affects both soil and forage productivity. Differing grasses may counteract some effects of compaction due to differences in their root architecture and ontogeny. To compare their resilience to soil compaction, three (ryegrass and fescue species' hybrids) forage grass cultivars comprising differing root architecture and ontogeny were compared in replicated field plots, together with a ryegrass and tall fescue variety as controls. Pre-compaction soil and forage properties were determined in spring using > four-year-old plots to generate baseline data. Half of each field plot was then artificially compacted using farm machinery. Forage dry matter yield (DMY) was determined over four cuts. After the final harvest, post compaction soil characteristics and root biomass (RB) were compared between grasses in the non-compacted and compacted soils. Pre-compaction data showed that soil under and ryegrass had similar water infiltration rates, higher than soil under tall fescue plots. Tiller density of the at this time was significantly higher than fescue but not the ryegrass control. Forage DMY was significantly lower ( < .001) with compacted soil at the first cut but, by the completion of the growing season, there was no effect of soil compaction on total DMY. Tall fescue had a higher total DMY than other grasses, which all produced similar annual yields. Soil bulk density and penetration resistance were higher, and grass tiller density was lower in compacted soils. Root biomass in compacted soils showed a tendency for cv Lp × Fg to have higher RB than the ryegrass at 0-15 cm depth. Overall, findings showed alternative grass root structures provide differing resilience to machinery compaction, and root biomass production can be encouraged without negative impacts on forage productivity.
由于气候变化，草原上干旱和洪水的发生频率不断增加，这增加了土壤压实的风险。土壤压实会影响土壤和牧草生产力。不同的草种可能因其根系结构和个体发育的差异而抵消压实的一些影响。为了比较它们对土壤压实的恢复力，在重复的田间试验地中比较了三种（黑麦草和羊茅属物种的杂交种）具有不同根系结构和个体发育的牧草品种，并以一种黑麦草和高羊茅品种作为对照。在春季使用四年以上的试验地测定压实前的土壤和牧草特性，以生成基线数据。然后使用农用机械对每个田间试验地的一半进行人工压实。在四次刈割期间测定牧草干物质产量（DMY）。在最后一次收获后，比较了未压实和压实土壤中不同草种的压实后土壤特性和根生物量（RB）。压实前的数据表明，鸭茅和黑麦草下的土壤具有相似的水分渗透率，高于高羊茅试验地的土壤。此时鸭茅的分蘖密度显著高于羊茅，但低于黑麦草对照。第一次刈割时，压实土壤的牧草DMY显著较低（P<0.001），但到生长季节结束时，土壤压实对总DMY没有影响。高羊茅的总DMY高于其他草种，其他草种的年产量相似。压实土壤的土壤容重和穿透阻力较高，草的分蘖密度较低。在压实土壤中，0-15厘米深度处，鸭茅cv Lp×Fg的根生物量有高于黑麦草的趋势。总体而言，研究结果表明，不同的草根结构对机械压实具有不同的恢复力，可以在不负面影响牧草生产力的情况下促进根生物量的生产。
