Mikha Maysoon M, Benjamin Joseph G, Vigil Merle F, Poss David J
US Department of Agricultural, Agricultural Research Service, Central Great Plain Research Station, Akron, Colorado, United States of America.
PLoS One. 2017 Apr 27;12(4):e0175533. doi: 10.1371/journal.pone.0175533. eCollection 2017.
Soil loss through wind and water erosion is an ongoing problem in semiarid regions. A thin layer of top soil loss over a hectare of cropland could be corresponding to tons of productive soil loss per hectare. The objectives of this study were to evaluate the influence of beef feedlot manure, tillage and legume grass mixtures on changes in soil quality and nutrient components. The study was initiated in 2006 on an eroded site near Akron, Colorado, on a Norka-Colby very-fine sandy loam (fine-silty, mixed, mesic, Aridic, Argiustolls). Tillage treatments were no-tillage, shallow tillage (sweeps operations with V-blade) and deep tillage (DT; moldboard plow operations). In one set of plots, DT was implemented biannually (DT-2); and in another set the DT was done once at the initiation of the experiment in 2006. Amendments consisted of beef manure and urea (46-0-0), N fertilizer. Both amendments were added at low and high rates. A control treatment, with no fertilizer or manure added, was included with no-tillage and shallow tillage only. Six years of manure addition and tillage significantly altered soil chemical properties compared with fertilizer and grass legume mixtures. Across all the tillage treatments, at the 0-30 cm depth, soil pH from 2006 to 2012, was reduced 1.8 fold with high-manure compared with high-fertilizer treatment. Soil EC, Na, and SAR increased by 2.7 fold while soil P increase by 3.5 fold with high-manure treatment compared with low-manure from 2006 to 2012 across all the tillage treatments at the surface 0-30 cm. Soil organic carbon associated with high-manure was 71% higher than low-manure and 230% higher than high-fertilizer treatments in the 0-60 cm depth. Similar patterns were observed with soil total N. Overall, manure amendments greatly improved the soil nutrient status on this eroded site. However, the legume grass mixtures showed little effect on improving soils chemical properties. The micronutrients supplied by manure improved the soil nutrient status compared with inorganic fertilizer, the grass, and the grass-legume treatments. We concluded that more than six years are needed to measure significant improvements in soil quality from specific treatments, specifically fertilizer, grasses, and grass-legume mixtures in such eroded crop land.
在半干旱地区，风蚀和水蚀造成的土壤流失是一个持续存在的问题。每公顷农田流失一层薄薄的表层土壤，可能相当于每公顷流失数吨肥沃土壤。本研究的目的是评估肉牛饲养场粪便、耕作方式和豆科牧草混合物对土壤质量和养分成分变化的影响。该研究于2006年在科罗拉多州阿克伦附近的一个侵蚀地开始，该地土壤为诺尔卡-科尔比极细砂壤土（细粉质、混合、中生、干旱、强钙质土）。耕作处理包括免耕、浅耕（用V型犁进行耙地作业）和深耕（用铧式犁作业）。在一组试验田中，深耕每两年进行一次（DT-2）；在另一组试验田中，深耕在2006年试验开始时进行了一次。改良剂包括牛粪和尿素（46-0-0）氮肥。两种改良剂都以低量和高量添加。仅在免耕和浅耕处理中设置了一个不添加肥料或粪便的对照处理。与肥料和豆科牧草混合物相比，六年的粪便添加和耕作显著改变了土壤化学性质。在所有耕作处理中，在0-30厘米深度处，与高量肥料处理相比，2006年至2012年期间，高量粪便处理使土壤pH值降低了1.8倍。在0-30厘米表层，2006年至2012年期间，与低量粪便处理相比，高量粪便处理使土壤电导率、钠和钠吸附比增加了2.7倍，而土壤磷增加了3.5倍。在0-60厘米深度处，与高量肥料处理相比，与高量粪便相关的土壤有机碳高出71%，比低量粪便处理高出230%。土壤全氮也观察到类似的模式。总体而言，粪便改良剂极大地改善了该侵蚀地的土壤养分状况。然而，豆科牧草混合物对改善土壤化学性质的效果甚微。与无机肥料、牧草和豆科牧草处理相比，粪便提供的微量营养素改善了土壤养分状况。我们得出结论，需要六年以上的时间才能衡量特定处理（特别是肥料、牧草和豆科牧草混合物）对这种侵蚀农田土壤质量的显著改善。
