Assessing long term effects of compost fertilization on soil fertility and nitrogen mineralization rate

Background

Fertilization with organic waste compost can close the nutrient cycles between urban and rural environments. However, its effect on yield and soil fertility must be investigated.

Aim

This study investigated the long-term effect of compost on soil nutrient and potentially toxic elements (PTEs) concentration, nutrient budgets, and nitrogen (N) mineralization and efficiency.

Methods

After 21 years of annual compost application (100/400 kg N ha^–1 year^–1 [100BC/400BC]) alone and combined with mineral fertilization, soil was analyzed for pH, organic carbon (SOC), nutrient (total N and P, N_min, extractable CAL-P, CAL-K, and Mg), and PTE (Cu, Ni, Zn) concentrations. Yields were recorded and nutrient/PTE budgets and apparent net mineralization (ANM, only 2019) were calculated.

Results

N efficiency was the highest in maize and for mineral fertilization. Compost application led to lower N efficiencies, but increased ANM, SOC, pH, and soil N, and surpluses of N, P, and all PTEs. Higher PTE concentrations were only found in 400BC for Cu. Nutrient budgets correlated with soil nutrient concentration. A surplus of 16.1 kg P ha^–1 year^–1 and 19.5 kg K ha^–1 year^–1 resulted in 1 mg kg^–1 increase in CAL-P and CAL-K over 21 years.

Conclusion

Compost application supplies nutrients to crops with a minor risk of soil-accumulation of PTEs. However, the nutrient stoichiometry provided by compost does not match crop offtakes causing imbalances. Synchronization of compost N mineralization and plant N demand does not match and limits the yield effect. In winter wheat only 65–70% of N mineralization occurred during the growth period.     

贺兰山野化牦牛秋季昼间行为时间分配和活动规律

2010年9月15²5日,采用瞬时扫描法和所有事件取样法对贺兰山野化牦牛进行行为观察,建立了牦牛的行为谱,并将相关行为进行分类,即运动、摄食、休息、社群和其他行为。研究表明:牦牛秋季昼间行为的分配比例最高为运动行为(39.85±1.73)%,其次是摄食(33.33±2.50)%和休息(23.78±3.75)%行为,社群(0.99±0.27)%和其他(2.05±0.18)%较低。运动在8:0025日,采用瞬时扫描法和所有事件取样法对贺兰山野化牦牛进行行为观察,建立了牦牛的行为谱,并将相关行为进行分类,即运动、摄食、休息、社群和其他行为。研究表明:牦牛秋季昼间行为的分配比例最高为运动行为(39.85±1.73)%,其次是摄食(33.33±2.50)%和休息(23.78±3.75)%行为,社群(0.99±0.27)%和其他(2.05±0.18)%较低。运动在8:00¹0:00,14:0010:00,14:00¹6:00时有明显的高峰期,摄食高峰期出现在9:0016:00时有明显的高峰期,摄食高峰期出现在9:00¹0:00时和15:0010:00时和15:00¹6:00时,休息在12:0016:00时,休息在12:00¹3:00时出现高峰期。采用2个独立样本的Mann-WhitneyU检验对不同年龄的牦牛行为进行比较,年龄因素对牦牛运动、摄食、休息和其他行为影响不显著(P>0.05),但对社群行为影响显著(P<0.05)。     

浅谈建筑工程预算存在的问题及对策分析

在实际建筑工程中,工程预算的作用是不可估量的。如：提高企业效益、加强企业效益和简化编制施工计划等,所以在实际建设工程中要加强管理。本文主要介绍建筑工程预算存在的问题及对策。     

Do tillage and conversion of grassland to cropland always deplete soil organic carbon?

ABSTRACT

Conversion of grassland to cropland is widely reported to deplete soil organic carbon (SOC) largely due to tillage effects on the decomposition of SOC. However, most studies report on long-term changes in SOC following the conversion and little is known about the changes in the short term. Net ecosystem carbon budget (NECB) measures the difference between total C input (i.e., manure, above- and below-ground plant residues) and C loss through heterotrophic respiration (RH). However, most studies that report temporal SOC do not report other components of the NECB like RH, total C inputs and often do not include the cumulative annualized change of these components. This review evaluated the change in C input, RH, NECB and SOC after conversion of permanent/continuous grassland to cropland within 5 years after the conversion. We also reviewed and compared no-tillage and conventional tillage on SOC storage and accumulation. Total C input was higher in grassland than cropland largely due to high root biomass, as opposed to aboveground residue, and therefore grassland tended to have higher NECB. Despite higher NECB in grassland, the SOC stocks in cropland (cornfield) converted from grassland were greater than that in continuous grassland within first 2–3 years of conversion. The combination of manure C addition and tillage in cropland showed potential to maintain NECB and increase SOC. Within the continuous grassland C addition alone increased NECB but did not result in a corresponding increase in SOC. Residue retention and manure addition are recognized as good practices for increasing SOC, this study however, shows that combining them with occasional tillage, especially in managed grasslands, could increase the rate of SOC storage in soils.     

成年黄山短尾猴春季昼间行为时间分配

2007年3～5月,采用焦点动物取样法对黄山野生猴谷YA1群黄山短尾猴成年个体行为时间分配进行系统观察.数据分析显示:黄山短尾猴成年个体日活动行为主要为休息(59.72%)、理毛(17.50%)和觅食(14.82%),其他行为如漫游(5.86%)、玩耍(0.04%)和其他(1.64%)时间花费较少,觅食高峰与投喂时间基本一致.老年组个体比成年组个体花费较多的时间用于休息(Z=-5.811,P＜0.01)和理毛(Z=-4.913,P＜0.01),较少时间漫游(Z=-3.989,P＜0.01).雄性个体花费较多时间休息(Z=-3.577,P＜0.01)而雌性个体花费大量时间进行理毛(Z=-3.134,P＜0.01).哺乳期雌性漫游行为(Z=-2.9541,P＜0.01)低于非哺乳期雌性个体,其他行为(Z=-2.9541,P＜0.01)明显高于非哺乳期雌性,而觅食行为(Z=-0.1773,P＞0.05)无显著差异性.结果表明人工投喂是导致其行为时间分配的主要原因.     

盐度和饵料对中国对虾碳收支的影响_

通过内生长实验的方法测定了中国对虾在不同盐度下摄食日本刺沙蚕及盐度３１海水中摄食日本棘少蚕和配合饲料的碳收支。结果显示,盐度５－３５范围内,水温２５℃时,对虾的碳摄食量在盐度１３时达到最大为６１．６４;而最适生长的盐度条件为２０,此时的碳利用效率最高为２５．８４％,碳的特定生长率最大为３．８９％。     

盐度对台湾红罗非鱼能量收支的影响

在水温２８℃的条件下,不限量投喂颗粒饵料,测定了台湾红罗非鱼在淡水和盐度为７,１４,２、,２８和３５％的能量收支。结果表明;盐度对台湾红罗非鱼的特定生长率,转化效率和最大摄食率均有显著影响,盐度为１４‰时,特定生长率和转化效率均达到最高水平,分别为１．４３％和５１．８８％,此时,摄食率也达了大,每天为体重的２．７５％,盐度对吸收效率无显著影响,对物质,蛋白质和能量的吸收效率的平均值分别为６２．９８     

Integrated assessment of catchment suspended sediment budgets: a Zambian example

In many developing countries, the management of sediment‐related environmental problems is severely hampered by a lack of information on sediment mobilization and delivery in river basins. The sediment budget concept represents a valuable framework for assembling such information, which can, in turn, be used to assist with the design and implementation of soil erosion and sediment control policies. However, the information necessary to construct a catchment sediment budget is difficult to assemble. Against this background, an integrated approach to establishing a catchment suspended sediment budget, involving a river monitoring station, the use of ¹³⁷Cs measurements to estimate soil erosion and deposition and floodplain accumulation rates within the catchment, and sediment source fingerprinting, has been developed and tested in the 63 km² catchment of the upper Kaleya River in southern Zambia. The approach developed not only provides detailed information on individual components of the suspended sediment delivery system, but also permits the establishment of the overall catchment sediment budget. A sediment budget for the upper Kaleya catchment is presented and both its key features and its wider implications for catchment management are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

投喂频率对刺参(Apostichopus japonicus)生长、体成分组成和能量收支的影响

在实验室条件下,对刺参(Apostichopus japonicus)在不同投喂频率条件下的生长、体成分组成和能量收支进行研究。实验设置4个投喂频率处理,分别每天投喂1(F1组)、2(F2组)、3(F3组)、4(F4组)次,共进行40 d。结果表明,F3组和F4组的刺参生长最快,其末体重均显著大于F1组和F2组(P0.05)。投喂频率越高,刺参的摄食量越大,F4组摄食量越高,为3.67 g/(d·ind),F3组和F4组刺参的摄食量均显著高于F1组和F2组(P0.05),但F3组和F4组没有显著差异(P0.05)。饵料转化率随投喂频率的增加而增加。其中,F4组的饵料转化率最高,为9.70%,而消化率却随投喂频率的增加而降低。投喂频率对刺参主要体成分组成影响不大。从各处理的能量收支方程来看,F1组和F2组的粪能占摄食能的比例显著低于F3组和F4组(P0.05),但占摄食能的比例均超过了50%,其呼吸能占摄食能的比例显著高于F3组和F4组。本研究表明,室内养殖刺参每天投喂3次最佳,排泄能和呼吸能较高可能是导致F1组生长不佳的主要原因。     

Simulating the effects of tax exemptions on fertiliser use in Benin by linking biophysical and economic models

The sluggish increase in the area productivity of staple crops is a major factor causing increased dependence of African countries on food imports. The increased use of mineral fertiliser may dramatically improve the food balance of many countries and result in lower food prices, higher food supply and consumption, and improved food security and nutritional status. In Benin, West Africa, political measures to improve farmers’ access to fertiliser are biased in favour of cotton production. This article simulates the impact of universal tax exemptions for fertiliser use on crop yields, food balances, and the use of land resources for the most important staple crops in Benin using a crop growth model and an agricultural sector model. The simulation results indicate that tax exemptions on fertiliser use could have positive effects on physical productivity and would increase food security until 2025 as compared to a baseline scenario. At the same time, the pressure on land resources would not be aggravated, so that better access to fertiliser may help to curb excessive cropland expansion in Benin.