Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-30 Cooperative journals: 《广西植物》
Abstract： To explore the effects of land use and ecological restoration on soil enzyme activities and C:N:P ratios in the karst ecosystem, three land use types [disturbed land, pasture grassland, and orchard forest (Loquat)] and four restoration types (evergreen forest, deciduous forest, evergreen-deciduous mixed forest, and natural restoration forest), which are long-term positioning observation experimental plots of the Huanjiang Observation and Research Station for Karst Ecosystems, were selected. We measured the activities of four soil enzymes [β-1,4-glucosidase (βG), β-1,4-N-acetylglucosidase (NAG), leucine aminopeptidase (LAP), and alkaline phosphatase (ALP)], and analyzed the relationship between activities level and the C:N:P ratios and soil-associated physical and chemical factors. The results were as follows: (1) Enzyme activities were higher in the three land use types than in the restoration types. In addition, the activities of the four enzymes, enzymatic N:P, and enzymatic C:P of pasture grassland were higher than those in the other restoration types. The βG and ALP activities in the evergreen-deciduous mixed and deciduous forests were significantly higher than those in the natural restoration and evergreen forest, and NAG activity in the evergreen forest was significantly higher than that in the other three restoration types. The enzymatic N:P ratios of the evergreen-deciduous mixed forests were significantly lower than those in the other restoration types, as was the enzymatic C:P ratio of the deciduous forest. In addition, vector analysis of the enzyme activity measurement ratio showed that all land use and restoration types were limited by P. (2) The activities of the four enzymes were positively correlated with organic C, ammonia N (NH4+-N), and nitrate N (NO3--N), whereas negatively correlated with total P (TP). βG activity was positively correlated with available P (AP) and ALP activity was positively correlated with total N (TN). (3) Redundancy analysis showed that the levels of TP, NH4+-N, NO3--N, and AP explained 38.3%, 9.5%, 9.3%, and 8.0%, respectively, of the changes in soil enzyme activity and C:N:P ratios. Based on these results, the different land use and restoration types in karst areas were shown to generally exist under the limitation of soil P, which implies that the fixation and transformation of P should be the focus of soil quality improvement in the land use development and restoration process. Furthermore, soil enzyme activities, C:P ratios, and AP contents in pasture grassland, evergreen-deciduous mixed forest, and deciduous forest were higher than those in the other land use and restoration types. The result indicates that forage and deciduous plants are important for soil nutrient cycling and should be considered in the process of karst land use and restoration.
Subjects: Biology >> Ecology submitted time 2017-11-29 Cooperative journals: 《中国生态农业学报》
Abstract： Based on a long-term experiment on maize-soybean relay intercropping system in Huanjiang Observation and Research Station for Karst Ecosystem, Chinese Academy of Sciences, the effects of straw in place of chemical potassium on the yield of spring maize and soil potassium balance were investigated, aiming to provide scientific basis for the rational use of straw and fertilizer in karst peak-cluster depression. The experiment was started in 2006, and the data were collected during 2010-2014. Four treatments with four repetitions were discussed in this study, including CK (no fertilizer), NPK (chemical fertilizer), C7S3 (in which 30% K from the straw and 70% K from the chemical fertilizer.), C4S6 (60% K from the straw and 30% from the chemical fertilizer). The results showed that: ⑴ the annual yields of spring maize in fertilization treatments during the 5 years were 4.12 ~ 4.17 times than that in no fertilizer treatment. The corn yields in C7S3 and C4S6 were 98.3% and 98.7% of that in NPK, respectively. The yields of grain and straw increased with time on. ⑵ compared with CK, fertilization application could significantly increase the K amount in maize straw with 2.21 ~ 2.53 times than that in CK. And fertilization application could significantly increase N, P and K absorption amounts in maize grain (P < 0.01), but there was no significant difference among fertilizer treatments (P > 0.05). ⑶ there were no significant differences for recovery efficiency, absorption efficiency, agronomic efficiency and partial factor productivity for potassium during the NPK, C7S3 and C4S6 treatments. ⑷ the annual surplus amount of potassium in NPK was 3.00 kg∙hm-2, which was higher than that in C7S3 (with minus 1.90 kg∙hm-2). The most annual surplus amount of potassium appeared in C4S6, with 8.22 kg∙hm-2, and the Surplus of potassium was 7.4%. ⑸ Compared to the beginning of the experiment(2006), soil rapidly available potassium declined by 15.9% in 2014; The fertilization application significantly increased the amount of rapidly available potassium (P < 0.01). The orders of annual amount of rapidly available potassium during 2010 ~ 2014 in fertilizer treatments were that: NPK > C7S3 > C4S6, with no difference in treatments (P > 0.05).⑹ after eight years of cultivation, soil slowly available potassium declined by 10.9% in CK, slightly declined in C4S6 with no more than 5%, slightly increased in NPK by 1.3%, and increased in C7S3 by 22.4%. Overall, the application of straw returning to replace some potassium fertilizer was suitable for the soil in karst peak-cluster depression, as it could not only maintain the yield of spring maize, but also sustain potassium dynamic balance. And 60% of the straw potassium substitution could be more suitable for sustaining potassium balance, while 30% of the straw potassium substitution could be more beneficial to improve soil slowly available potassium.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture submitted time 2017-11-09 Cooperative journals: 《中国生态农业学报》
Abstract：基于自2006 年在广西喀斯特峰丛洼地区开展的长期玉米/大豆套作定位施肥试验, 选择2010—2014 年监测数据, 探讨等氮量投入条件下, 不同比例有机肥替代无机氮肥对喀斯特峰丛洼地玉米/大豆套作系统作物产量及土壤养分的影响, 为喀斯特峰丛洼地农田作物高效施肥及提高土壤肥力提供理论依据。试验选取4 个处理:对照(不施肥, CK)、平衡施用化肥(NPK)、有机粪肥替代30%化肥氮(C7M3, 按氮素计算, 不z30%的PK 用无机肥补充, 肥料总量与NPK 处理相同, 有机粪肥为牛粪, 下同)、有机粪肥替代60%化肥氮(C4M6, 按氮素计算, 不足60%的PK 用无机肥补充), 每个处理4 次重复。于2010 年、2012 年、2014 年大豆收获后采集土壤样品, 测定土壤养分状况。结果表明: 1)施肥处理土壤有机质、全氮、速效磷及速效钾含量均高于CK 处理, 其中C4M6 处理有机质含量显著高于NPK 处理(PNPK>C7M3, 但施肥处理间差异不显著(P>0.05)。3)长期不施肥CK 处理玉米产量随着试验年限推移呈下降趋势, 降幅为5.45 g·m2·a1, 大豆产量却表现出增加趋势, 增幅为1.50 g·m2·a1。长期施肥处理中, 玉米和大豆产量总体呈增加趋势。4)施肥处理中, 玉米季表现为钾素亏缺(NPK 处理除外), 大豆季表现为氮素亏缺。综合两季作物, 只有C4M6 钾素表现亏缺, 亏缺量为7.9 kg·hm2。磷素在各施肥处理中盈余量较大, 分别为81.2 kg·hm2(NPK)、83.4 kg·hm2 (C7M3)和74.8 kg·hm2 (C4M6)。综上, 在喀斯特峰丛洼地玉米/大豆套作制度下, 基于作物产量及土壤养分表观平衡特征提出有机粪肥可以代替部分化肥施用, 在玉米季适当“减氮、稳磷和增钾”, 大豆季“稳氮、减磷和减钾”的施肥措施。
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