Soil Alkali-hydrolyzable Nitrogen Research Articles

坝上地区不同年代退耕还林生境的草本层植物多样性及影响因子

PDF HTML阅读 XML下载 导出引用 引用提醒 坝上地区不同年代退耕还林生境的草本层植物多样性及影响因子 DOI: 10.5846/stxb201912042631 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41671181） Herb diversity and its impact factors in different periods from 1970s to 2000s of the returning farmland to forest project in the Bashang Area of North China Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:退耕还林是坝上地区重要的生态修复工程，其生态效益日益受到广泛关注，但针对林下植物多样性保护功能的研究还较少，虽然草本层植被是森林生态系统服务功能的重要指标之一。为评估不同年代退耕还林生境的生物多样性，调查了20世纪70年代至21世纪初共4个年代退耕还林生境的草本层植物多样性，并与弃耕生境及自然林生境进行了对比。为进一步分析林下草本层植物多样性的影响因子，还分析了乔灌层植被、土壤理化性质与林下草本植物多样性的关系。结果显示，不同年代退耕还林的林下草本植物多样性未有显著差异，且均显著低于弃耕生境与自然林生境。草本层物种丰富度对土壤碱解氮含量、灌木层丰富度、灌木层密度具有显著的正响应，Simpson多样性主要与乔木层林木密度呈显著负相关。研究表明，不同年代退耕还林后的林下草本层植物多样性保护功能低于预期，而改善林分空间结构与建设模式可能利于提升其生物多样性保护功能。未来植被修复中需充分权衡生态系统不同服务功能之间的关系，因地制宜，宜林则林，宜草则草，重视自然恢复与多元化生态修复方式，以实现更好生态效益。 Abstract:Returning farmland to forest (RFTF) project is one of the most critical ecological restoration projects in Bashang area, and its ecological service value has been paid more and more attention. Although the herb layer of the artificial forest was a vital indicator to biodiversity conservation and ecosystem services, the relevant researches were much less than expected in this area. We surveyed herb diversities of these forests that were planted in four different periods from 1970s to 2000s of the returning farmland to forest project. Then, the herb diversity of returning farmland to forest habitat was compared with that in abandoned farmland and the natural forests. The effect of the soil character, tree and shrub layer on herb diversity was also analyzed. The results showed that there was no significant difference of herb diversity among different periods of RFTF projects. While all of them were significantly lower than that in the abandoned farmland and the natural forests species richness of herb layers was significantly and positively responded to the content of soil alkali-hydrolyzable nitrogen species richness and densities of shrub. The Simpson diversity of herb layer was negatively responded to the densities of tree. The research revealed that the herb diversities of RFTF habitats might be lower than that we expected, improving vertical spatial structures and construction mode might be helpful to increase the herb diversity level. In order to preferably realize ecological benefits of future ecological restoration projects in Bashang area, it needs to weigh the different relationships of ecological ecosystem service functions, choose ecological restoration methods based on local conditions, and emphasize the importance to natural restoration and diverse restoration methods. 参考文献 相似文献 引证文献

Effects of planting Caragana shrubs on soil nutrients and stoichiometries in desert steppe of Northwest China

Caragana korshinskii shrubs are widely planted in desert steppe of Northwest China to mitigate desert encroachment. Soil nutrients and stoichiometries reflect the cycling of soil organic matter in ecosystems. Thus, there is a dynamic balance between soil nutrients and stoichiometries due to the establishment of Caragana shrubs in this region. Here, soil nutrients and stoichiometries were characterized with different planting densities of Caragana shrubs (HD, high density, 4530 bundle/hm2; MD, mid density, 3670 bundle/hm2; LD, low density, 2560 bundle/hm2) to explore how the planting of Caragana shrubs affects soil nutrients and stoichiometries in desert steppe of Northwest China. The results showed that soil available phosphorus (AP) and soil total phosphorus (TP) had no significant differences between LD and control (CK) (p > 0.05). Further, soil organic carbon (SOC), soil total nitrogen (TN), and soil alkali-hydrolyzable nitrogen (AN) followed the order of HD > MD > LD > CK, indicating that the planting of Caragana shrubs had an increasing effect to soil nutrients, with the exception of AP and TP (p < 0.05), and the increasing effect gradually died down along soil profile. In addition, the planting of Caragana shrubs significantly affected soil stoichiometries. Specifically, soil N/P and C/P gradually increased with soil depth with fluctuation, while soil C/N decreased with soil depth. Besides, soil water content (SW), AP, AN, and SOC had strong positive effects on soil C/N, while they had strong negative effects on soil C/P and N/P, highlighting the importance of soil properties in determining soil stoichiometries. Overall, our results indicated that planting Caragana shrubs can improve levels of soil nutrients, and HD can be considered the optimal planting density for vegetation restoration in desert steppe. Nevertheless, the threshold of the planting density most favorable for the special climates must be identified through further study in this region.

Effects of Biogas Slurry Application on Crop Production and Soil Properties in a Rice–Wheat Rotation on Coastal Reclaimed Farmland

The field experiment of a rice–wheat rotation system was conducted on a coastal reclaimed farmland with different application rates of biogas slurry from a large-scale standardized hoggery. Crop yield, grain quality, and soil properties were examined to determine the appropriate application rate. At the slurry application rates of 480 m3 ha−1 for rice and 9.00–11.25 m3 ha−1 for wheat, grain yields of rice and wheat were 8.9 and 15.7% higher than those under conventional fertilization, respectively. When 840 m3 ha−1 biogas slurry was applied to the rice field, the grain amino acid content was significantly higher than that of conventionally fertilized rice. In the rice–wheat rotation system, under biogas slurry treatments, soil pH and EC did not significantly increase; the contents of soil Pb, Cr, Cu, and Zn were within allowable limits; the contents of soil alkali-hydrolyzable nitrogen were greatly increased and significantly higher than those under conventional fertilization treatment; and the content of soil organic matter had no significant difference with that under no fertilization treatment. Therefore, the recommended application rate of biogas slurry on coastal reclaimed farmland should be 480 and 9.00–11.25 m3 ha−1 for rice and wheat, respectively.

Updating the main vegetable fertilization index system for southern China

ABSTRACTHere, we established abundance and deficiency indices of soil nutrients and fertilization to generate a reference for the optimum fertilization dosage of the main vegetable crops in southern China under current production conditions. We consolidated 3414 field datasets about the main vegetable crops (leafy vegetables, gourds, legumes) in this region between 2010 and 2013. The nutrient abundance and deficiency index method was used to separate soil alkali-hydrolyzable nitrogen, available phosphorus, and available potassium levels into five groups based on relative vegetable yields (range: 50%–95%). Recommended fertilizer dosages were determined by obtaining values for nitrogen, phosphorus, and potassium by fitting optimum dosage against available nutrient content. Required fertilization levels were dependent on soil conditions and crop type. Comparison of the study results showed that available phosphorus and available potassium had significantly improved, whereas alkali-hydrolysable nitrogen in each level was similar.

Effect of N fertilization rate on soil alkali-hydrolyzable N, subtending leaf N concentration, fiber yield, and quality of cotton

Soil alkali-hydrolyzable nitrogen, which is sensitive to N fertilization rate, is one of the indicators of soil nitrogen supplying capacity. Two field experiments were conducted in Dongtai (120°19″ E, 32°52″ N), Jiangsu, China in 2009 and Dafeng (120°28″ E, 33°12″ N), Jiangsu province, China in 2010. Six nitrogen rates (0, 150, 300, 375, 450, and 600kgha−1) were used to study the effect of N fertilization rate on soil alkali-hydrolyzable nitrogen content (SAHNC), subtending leaf nitrogen concentration (SLNC), yield, and fiber quality. In both Dongtai and Dafeng experiment station, the highest yield (1709kgha−1), best quality (fiber length 30.6mm, fiber strength 31.6cNtex−1, micronaire 4.82), and highest N agronomic efficiency (2.03kgkg−1) were achieved at the nitrogen fertilization rate of 375kgha−1. The dynamics of SAHNC and SLNC could be simulated with a cubic and an exponential function, respectively. The changes in SAHNC were consistent with the changes in SLNC. Optimal average rate (0.276mgday−1) and duration (51.8days) of SAHNC rapid decline were similar to the values obtained at the nitrogen rate of 375kgha−1 at which cotton showed highest fiber yield, quality, and N agronomic efficiency. Thus, the levels and strategies of nitrogen fertilization can affect SAHNC dynamics. The N fertilization rate that optimizes soil alkali-hydrolyzable nitrogen content would optimize the subtending leaf nitrogen concentration and thereby increase the yield and quality of the cotton fiber.

Effects of two phenolic acids on root zone soil nutrients, soil enzyme activities and pod yield of peanut

In order to investigate the relationship between the accumulation of phenolic acids in peanut continuous cropping soil and the continuous cropping obstacle of peanut, the effects of p-hydroxy benzoic acid and cinnamic acid on peanut root zone soil nutrients, soil enzyme activities and yield of peanut were studied by pot experiment at three stages of peanut, i.e. the pegging stage of peanut (45 days after seedling), the early podding (75 days after seedling) and the end of podding (105 days after seedling) stages. The results showed that the peanut root zone soil nutrients and enzyme activities changed obviously under the two phenolic acids treatment, especially at the pegging stage of peanut. The soil alkali-hydrolyzable nitrogen, available phosphorus, available potassium, and soil enzyme activities (urease, sucrose, neutral phosphatase) were decreased significantly. At the early and end of podding stages of peanut, the effects of the two phenolic acids on peanut root zone soil nutrients and soil enzyme activities were under a weakening trend. The allelopathy of cinnamic acid was stronger than that of p-hydroxy benzoic acid at the same initial content. The pod yield per pot was reduced by 45.9% and 52.8%, while the pod number of per plant was reduced by 46.2% and 48.9% at higher concentration (80 mg·kg-1 dry soil) of p-hydroxy benzoic acid and cinnamic acid treatments, respectively.

Soil remediation of degraded coastal saline wetlands by irrigation with paper mill effluent and plowing

Combined with anti-waterlogging ditches, irrigation with treated paper mill effluent (TPME) and plowing were applied in this study to investigate the effects of remediation of degraded coastal saline-alkaline wetlands. Three treatments were employed, viz., control (CK), irrigated with 10 cm depth of TPME (I), and plowing to 20 cm deep before irrigating 10 cm depth of TPME (IP). Results show that both I-treatment and IP-treatment could improve soil structure by decreasing bulk density by 5% and 8%. Irrigation with TPME containing low salinity stimulated salts leaching instead of accumulating. With anti-waterlogging ditches, salts were drained out of soil. Irrigation with 10 cm depth of TPME lowered total soluble salts in soil and sodium adsorption ration by 33% and 8%, respectively, but there was no significant difference compared with CK, indicating that this irrigation rate was not heavy enough to remarkably reduce soil salinity and sodicity. Thus, irrigation rate should be enhanced in order to reach better effects of desalinization and desodication. Irrigation with TPME significantly increased soil organic matter, alkali-hydrolyzable nitrogen and available phosphorus due to the abundant organic matter in TPME. Plowing increased soil air circulation, so as to enhance mineralization of organic matter and lead to the loss of organic matter; however, plowing significantly improved soil alkali-hydrolyzable nitrogen and available phosphorus. Improvements of physicochemical properties in I-treatment and IP-treatment both boosted soil microbial population and activity. Microbial biomass carbon increased significantly by 327% (I-treatment) and 451% (IP-treatment), while soil respiration increased significantly by 316% (I-treatment) and 386% (IP-treatment). Urease and dehydrogenase activities in both I-treatment and IP-treatment were significantly higher than that in CK. Phosphatase in IP-treatment was significantly higher than that in CK. Compared to I-treatment, IP-treatment improved all of the soil properties except for soil organic matter. The key to remediation of degraded saline-alkaline wetlands is to decrease soil salinity and sodicity; thus, irrigation plus plowing could be an ideal method of soil remediation.

Spatial and Temporal Variability of Available Nutrient in Cotton Field at Flower and Boll Stage and Its Effect on Lint Yield and Fiber Quality

Flower and boll stage is a key period for lint yield and fiber quality. Studying the spatial and temporal variability of available nutrient in cotton field at flower and boll stage can provide theoretical base for exploring the physiological measurements to improve lint yield and fiber quality. The field experiments were carried out in 2004 at application levels of 0,120,240,360,and 480 kg N ha-1(marked N0,N1,N2,N3,N4 respectively) ,185 kg P ha-1 and 118 kg K ha-1 in Anyang and Nanjing,the typical representatives for ecological regions in Yellow River Valley and the middle lower reaches of Yangtze River Valley in China. The results indicated that,in the process of growth,the content of soil alkali-hydrolyzable nitrogen in 0–60 cm soil layers of N0 treatment presented the trend of decreasing firstly and increasing then. While that of other treatments decreased firstly,increased after topdressing,decreased again,and increased after the beginning of boll opening. Soil available phosphorus and available potassium in 0–60 cm soil layers at two experimental locations presented the similar trends of decreasing firstly and increasing then. Soil available nutrient in 0–60 cm soil layers decreased with the deepening of the layer. Soil alkali-hydrolyzable nitrogen and available phosphorus in the same soil layer of N1,N2,N3,and N4 treatments in Nanjing presented the similar decreasing as the horizontal distance to cotton plant increased,and in N0 treatment,there was no significant variation in alkali-hydrolyzable nitrogen and available phosphorus contents. The spatial and temporal variability for soil alkali-hydrolyzable nitrogen was more significant in Nanjing than in Anyang. While for soil available phosphorus,it was more significant in Anyang than in Nanjing. Soil available potassium in 0–60 cm soil layers in Nanjing and in 20–60 cm soil layers in Anyang presented thesimilar decreasing with the increasing of horizontal distance to cotton plant,while that in 0–20 cm soil layers in Anyang increasing. As a result,at the nitrogen application level of 360 kg ha-1 for Anyang and 240 kg ha-1 for Nanjing,yield components were the relatively optimal,yield was the maximum and the fiber quality of length and strength was better. So,in order to increase lint yield and fiber quality,different ecological regions should follow the spatial and temporal variability of soil available nutrient in cotton field at flower and boll stage to confirm the optimal fertilizer level.