Gliricidia sepium Carbon Inputs and Soil Carbon Pools in a Costa Rican Alley Cropping System

Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO₂ emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [? N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m^{? 2} y^{? 1}, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m^{? 2}y^{? 1}. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and ?N alley crops compared to 49 and 50 years in the + N and ?N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and ?N treatments respectively.     

Enhancing ecosystem services in vineyards: using cover crops to decrease botrytis bunch rot severity

Botrytis bunch rot is a disease that causes loss of yield and quality in many fruit and vegetable crops in temperate climates worldwide. The rot is caused by the fungus Botrytis cinerea, a saprophytic necrotroph. In grapes, the presence of the fungus can reduce yield, taint wine and increase its sensitivity to oxidation. In the current work, inter-row phacelia and ryegrass were mulched in situ in winter 2005 and compared with a bare ground control. The mulches were applied under 10-year-old Chardonnay vines in a 10-replicate randomized block design in New Zealand. Functional soil biological activity increased by 1.5–4.5 times in the two cover crop treatments compared with the control, an effect related to elevated soil moisture in these treatments. This increase in soil moisture and a higher rate of soil biological activity increased vine debris degradation, reduced B. cinerea primary inoculum on the debris and decreased B. cinerea severity at flowering (December 2005) and harvest (April 2006). These results show the potential of mulched cover crops to enhance soil ecosystem services, reduce variable costs and improve the sustainability of viticulture and potentially other agricultural systems, in temperate climates worldwide.     

大豆地膜覆盖栽培技术

分析了地膜覆盖栽培大豆增产的原因,重点介绍了大豆全生育期地膜覆盖栽培技术中整地与施肥,选种,覆膜,播种及田间管理的技术措施。     

景观环境常用有机地表覆盖物的吸水 性能研究

有机地表覆盖物具有滞留雨水、降低地表径流的作用。为优选适用于城市雨水管理的有机地表覆盖物,选择16种景观环境常用有机地表覆盖物材料,对其材料密度、质量吸水倍率、质量吸水速率、体积吸水倍率、体积吸水速率和饱和时长进行了测定。结果表明：1)质量吸水倍率：锯末和花生壳表现最好,蚯蚓粪表现最差;2)质量吸水速率：各材料0~10min内的质量吸水速率均为最高,而后下降较快,第10min时,16种材料的质量吸水率占比平均为75.60%,最低的核桃壳为51.22%,最高的复叶槭粉碎物达89.42%;3)体积吸水倍率：锯末、蚯蚓粪、花生壳和柳树皮的体积吸水倍率表现较好,松针和打磨松树皮(3~5cm)表现较差;4)体积吸水速率：各材料0~10min内的体积吸水速率规律与质量吸水速率一致,打磨松树皮(3~5cm)、松针和核桃壳的体积吸水速率较小,最高的锯末是打磨松树皮(3~5cm)的8.83倍;5)饱和时长：花生壳用时最短,25min就达到饱和状态,松塔壳用时最长,为60min。研究结果可为城市地面及屋顶绿化所需有机地表覆盖物的优选提供参考依据。     

砂石与秸秆覆盖对风沙土水分蒸发特性的影响

探究不同厚度的砂石和秸秆覆盖对辽西北风沙土土壤水分蒸发的影响机理,特别是在不同初始含水率下的影响,并探索抑制辽西北风沙地土壤水分蒸发的最佳模式,也为风沙区植被建设提供理论基础。首次以辽西北风沙土为研究对象,运用自行设计的蒸发桶进行为期20天的室内蒸发模拟试验,研究土壤蒸发量随蒸发时间的变化规律。结果表明,砂石与秸秆覆盖能够抑制土壤水分蒸发,随着初始含水率增大,砂石与秸秆覆盖厚度越厚,其保持土壤水分的效果就越强。     

Nitrogen fixation during decomposition of sugarcane (Saccharum officinarum) is an important contribution to nutrient supply in traditional dryland agricultural systems of Hawai'i

Nitrogen (N) is unique among essential elements required for life, in that it must be fixed from the vast atmospheric reservoir before most organisms can use it. Prior to industrial nitrogen fixation, many agricultural systems were limited in their productivity by N. What sustained N in the ancient Hawaiian dryland (rain-fed) agricultural systems that lacked legumes or other known significant N inputs? N-fixation during sugarcane (Saccharum officinarum) growth and litter decomposition was examined in settings representing pre-European Hawaiian agriculture. We did not detect associative N-fixation during the growth of five Hawaiian sugarcane cultivars. In contrast, N-fixation during the decomposition of leaf and stalk material was important. We found that the depth of the mulch layer significantly affected N-fixation levels during decomposition; values of N-fixation in different depths of senesced leaf litter ranged from 0.69 to 1.36?gN/kg of litter integrated over the lifetime of decomposition. Compared to senesced leaf litter, N-fixation during decomposition of non-senesced leaf litter was ～77% and stalk material ～140% per unit mass. Peak rates of N fixation occurred between 200 and 400 days of decomposition, and ranged from 1.37 to 3.27?gN/kg/yr. Our empirical results were extrapolated to represent the traditional Hawaiian cropping system; we calculated N-fixation inputs of 4.8–39.0 kgN/ha/yr, with fixed N adding 17–40% of the amount of N added through litter. Findings indicate that significant N may be introduced into natural cropping systems through mulching practices and that small changes in practices greatly alter the total inputs. The use of mulch was likely an important source of N in pre-industrial settings and may be used in contemporary systems to reduce nitrogen fertilizer requirements.     

回收废旧PE和PP塑料生产防滑板的工艺开发

在分析了我国废旧PE和PP塑料薄膜的产生、回收和利用现状的基础上，针对污染较严重、并与其它塑料混杂的PP和PE薄膜回收困难、回收率低的现实，开发了一种分离回收农用地膜和垃圾中的塑料薄膜制造防滑板的生产工艺，对工艺的各个关键环节进行了讨论，并对制作防滑板的工艺进行了经济分析，证实防滑板是污染严重的废PE和PP膜回收利用一个较为经济和环保的最终产品出路。     

基于样方法开展黄淮海蔬菜主产区地膜残留状况研究

[目的]为客观了解黄淮海蔬菜主产区露地蔬菜地膜使用、回收和残留情况。[方法]文章选择了有代表性的安徽省和县、河南省扶沟县、山东省寿光市和天津市武清区等地区进行实地调查,并采用样方法开展土壤地膜残留试验研究。[结果] 4个县(市/区)地膜使用量相差较大,从大到小依次为：寿光市>武清区>扶沟县>和县;覆膜厚度符合国家相关标准的占比较低;地膜回收率相差较大,武清区、寿光市地膜回收理想,分别达到100%和97.16%,和县为71.15%,扶沟县最低,为34.13%;回收的地膜处置方式相似,主要是填埋或废弃;和县、扶沟县和寿光市地膜平均残留量分别为18.10、3.31和1.39 kg/hm²。[结论]黄淮海蔬菜主产区的地膜使用量较大,覆膜厚度符合国家相关标准的占比较低,地膜回收率差异大,一些地区回收率不高,回收的地膜以填埋或废弃为主要处置方式,均存在不同程度的地膜残留问题。为加强地膜回收利用和降低残膜污染,需建立健全政府主导、企业参与、农户配合的源头控制、过程管控、末端循环利用等全过程管控机制。