祁连山区草地土壤氮空间分布格局

就祁连山草原生态系统土壤氮在不同时期、不同放牧强度条件及不同土层深度条件下空间分布进行了试验研究,运用回归分析及方差显著性检验对土壤全氮含量进行了分析,结果发现3种不同放牧条件下,祁连山草地土壤氮的变化量差异显著;同时发现不同土层深度和土壤容积质量与土壤全氮量之间存在很好的线性相关关系,从而指出合理放牧会全面提高土壤质量。     

Biological nitrogen fixing capacity and biomass production of different understorey pastures in a Pinus radiata-pasture agroforestry system in New Zealand

Quantitative field measurements of biological nitrogen fixation (BNF) and biomass production by four different understorey pastures in a Pinus radiata-pasture agroforestry system were determined over a period of one year. The trees were two years old at the beginning of this study and the understorey pastures were being cut and removed for silage. The BNF was determined using the ¹⁵N dilution technique. Pastures of ryegrass+clover, cocksfoot+clover, phalaris+clover and lucerne were used. Substantial amounts of BNF were found (71 to 230 kg N ha^–1 year^–1) with lucerne showing the highest N fixation. However, lucerne derived only 71 to 72% of its N from the atmosphere (%Ndfa) during the spring/summer period compared to 83–97% with clovers, thus the net N demand from the soil was substantially higher with lucerne. This caused increased N stress to the trees. Clover in ryegrass+clover pasture fixed more N than the other grass+clover pastures. Although pasture position in relation to trees did not affect annual pasture total DMY and %Ndfa, pastures north of tree row grew better than those in other positions. Trees significantly affected the BNF of legumes and the botanical composition of pastures with highest BNF and legume production occurring in pastures midway between two rows of trees. These results suggest that it would be advantageous to evaluate different legumes and grasses for tolerance of shade and moisture stress in future studies. As the trees studied were only 1.5 to 3 m in height, their effects on BNF, seasonal pasture biomass production and botanical composition are expected to increase with tree dominance in the ecosystem with time. Amounts of N fixed were related to the productivity (i.e. dry matter and N yield) and seasonal persistence of the legumes. The productivity was high in spring and summer and low in autumn and winter.     

8种土壤改良剂对多年生黑麦草草坪质量的影响

在兰州新区通过田间小区试验,研究了8种土壤改良剂对多年生黑麦草草坪质量的影响。结果表明:8种土壤改良剂都提高了草坪叶绿素含量,其中,7种处理(除硫磺粉处理)都增大了草坪草的密度、高度、地下生物量和地上生物量,6种处理(除硫磺粉、硫磺粉+磷矿粉处理)都增大了叶宽和盖度,"肥帝溉"处理均为最大处理(P0.05),其相应草坪质量指标最大值分别为,叶绿素含量为3.1 mg/g,密度为2.0株/cm~2,叶宽为1.8 mm,盖度为95.3%,高度为10.9cm,地下生物量为709.3 g/m~2,地上生物量为638.6g/m~2;延长草坪绿期方面,"美魅"+过磷酸钙处理为186 d,与对照差异显著(P0.05)。8个处理和对照(CK)的草坪质量综合评价高低顺序为,"肥帝溉"大量元素水溶肥料"康地宝"盐碱土壤改良剂"美魅"土壤改良剂+过磷酸钙过磷酸钙+石膏粉过磷酸钙硫磺粉+磷矿粉"甘云翼"对照硫磺粉。     

青藏铁路植被恢复和“黑土型”退化草地治理的实践与启示

由于高、寒和旱的独特特点,青藏高原生态系统具有特殊的环境敏感性和脆弱性。近年来,工程扰动、放牧等人类活动的加剧对青藏高原生态系统稳定性的影响日渐凸显,集中表现为植被退化、土壤贫瘠化和水土流失加剧等。目前,为了尽可能避免人类活动对生态系统造成的负面影响,遏制生态环境的进一步恶化,已采用了多种方式和手段进行环境保护和植被恢复。本研究以青藏铁路工程植被恢复和"黑土型"退化草地治理两个典型案例为例,总结了青藏高原进行植被恢复的经验,提出了青藏高原植被恢复的基本原则和注意事项,对今后青藏高原工程扰动和草地退化后进行植被恢复具有指导意义。     

不同种植年限苜蓿地土壤理化性状

本研究分析了半干旱区不同种植年限苜蓿(Medicago sativa)地土壤理化性状。结果表明,随着苜蓿种植年限的增加,0-100 cm土层土壤容重出现不规律的波动,苜蓿地土壤容重值整体偏大;土壤有机质随种植年限的增加而增大,随土层深度增加而显著减小(P0.01),并且在种植5年的苜蓿地中提高最明显,在种植8年的苜蓿地中最低。各年限苜蓿地均表现出土壤有机质的"表聚性"。在一定的种植年限范围内,种植苜蓿对土壤有机质具有累积作用;土壤全氮含量随苜蓿种植年限的增长表现为先增大后减小的趋势,随土层深度的加深而逐渐减小,种植苜蓿4年时土壤全氮含量最大,8年时苜蓿地土壤全氮含量最低,并且土壤全氮含量主要集中于0-40 cm土层,全氮显著累积作用于表层土壤;土壤硝态氮随着苜蓿种植年限的增加而先增加后减小,随着土层的加深而逐渐降低,表层土壤对土壤硝态氮有累积作用,并且与苜蓿种植时间长短有显著相关性(P0.05)。而铵态氮含量在剖面上变化不大,与苜蓿生长年限没有显著相关性(P0.05)。今后需从栽培苜蓿草地的管理措施上深入探讨栽培苜蓿地的最佳种植和利用年限。     

滇西北高寒地区牧草混播组合的筛选

为提高香格里拉高寒地区饲草生产能力,在小中甸镇开展了牧草混播组合试验.试验设5个混播组合(A1、A2、A3、A4、A5),随机区组设计,连续两年对牧草产量和组分进行测定,第2年取混合样对营养含量进行分析.结果表明,A1和A5组合牧草产量显著高于A2、A3和A4 (P＜0.05);A3、A1、A5年度间群落组分变化不大,稳定性较强;A2、A4、A5的粗蛋白含量较高,均超过24％.3项指标综合考虑,A1[安巴鸭茅(Dactylis glomerata cv.Anmba)+草地休衣白三叶(Trifolium repens cv.Grasslands huia)+红三叶(T.pratense)]和A5[安巴鸭茅+雅晴多年生黑麦草(Lolium perenne cv.Yatsyn)+海法白三叶(T.repens cv.Haifa)+普纳菊苣(Cichorium intybus cv.Puna)]适宜在香格里拉高寒地区种植应用.     

Study on the Nutritional-ecologic Environment of Fe,Cu,Mn,Zn and Se in Yili Summer Pasture of Xinjiang (Ⅰ)

This experiment objective was to study the Fe, Cu, Mn, Zn, Se five kinds of trace element contents, distribution characteristics and mutual relations in the soil-grass-water (stream) in Yili pastoral area of Xinjiang, to evaluate the trace elements nutritional-ecologic environment of Yili summer pasture in Xinjiang.At the altitudinal belt of 1400 to 2999 m of the summer pasture of the Karajon grassland (South slope) and Tangbula grassland (North slope) of Yili, Xinjiang, the samples of soil (n=75), herbage (n=75), stream water (n=75) were collected according to the altitude, to determine their contents of Fe, Cu, Mn, Zn and Se for evaluating the nutritional-ecologic environment of trace elements of Yili summer pasture.The results showed that the contents of Fe, Cu, Mn, Zn in the soil of summer pasture on average were 15 418.4, 32.6, 474.5 and 115.8 mg/kg, respectively;And 446.0, 7.8, 85.7 and 41.9 mg/kg, respectively in forage;The correlation (R²) of the contents of Fe, Cu, Mn and Zn between soil and forage were 0.43, 0.82, 0.47 and 0.72, respectively;The changes of Fe, Cu, Mn and Zn contents in the soil and forage were not significantly related with the altitude.There were no the 4 elements mentioned above in river streams, there was no Se in the soil and forage, and there was infinitesimal of Se in the river streams.It was concluded that in Yili summer pasture there were excessive Fe, suitable Zn and Mn, insufficient Cu, and more insufficient Se.     

Effects of the nitrification inhibitor dicyandiamide on soil mineral N, pasture yield, nutrient uptake and pasture quality in a grazed pasture system

Recent lysimeter studies have demonstrated that the nitrification inhibitor, dicyandiamide (DCD), can reduce nitrate (NO) leaching losses from cow urine patches in grazed pasture systems. The objective of this study was to quantify the effects of fine particle suspension (FPS) DCD on soil mineral N components, pasture yield, nutrient uptake and pasture quality under grazed pasture conditions. A field study was conducted on the Lincoln University dairy farm, Canterbury, New Zealand, from 2002 to 2006. FPS DCD was applied to grazed pasture plots at 10 kg ha^?1 in early May in addition to applied cow urine patches at a nitrogen (N) loading rate of 1000 kg N ha^?1, with DCD reapplied in early August. Soil mineral N levels in the urine patches were monitored. Pasture yield, N and cation concentrations and uptake were measured in treatment urine patches and inter‐urine areas of the pasture. Comparisons were made with control plots which did not receive DCD. NO levels under the DCD‐treated urine patches (0–7.5 cm) were in the order of 10 kg N ha^?1 compared with 40–80 kg N ha^?1 under untreated patches, and soil ammonium (NH) levels were consistently higher under the DCD‐treated patches. The DCD significantly and consistently increased pasture yield in both the urine patches, and inter‐urine areas of the pasture in all 4 years of the trial. Mean annual dry matter (DM) yields over 4 years were inter‐urine areas, 10.3; inter‐urine + DCD, 12.4; urine, 12.4 and urine +DCD 16.0 t DM ha^?1, representing an average DM yield increase of 20 and 29% in inter‐urine and urine patch areas, respectively. On a whole paddock basis, the increase in annual DM yield resulting from DCD application was estimated to be 21%. N, calcium (Ca), magnesium (Mg) and potassium (K) concentrations in pasture were unaffected by treatment with DCD; however, total annual uptake of these nutrients by pasture was significantly higher in all years where DCD had been applied. Pasture DM, protein, carbohydrate, metabolizable energy and fibre levels and sward clover content were not affected by treatment with DCD. The results demonstrate the agronomic value of the DCD treatment in addition to the environmental benefits in a grazed pasture system.     

Osteomalacia as a result of phosphorus deficiency in beef cattle grazing subtropical native pastures in Uruguay

We investigated 2 outbreaks of osteomalacia as a result of phosphorus (P) deficiency in herds of lactating beef cows grazing subtropical native pastures in Uruguay. Cows exhibited pica, difficulty to stand and walk, rib fractures, and body weight loss even with adequate forage availability. Osteopenia and severe osteomalacia were observed on gross and histologic examination. The concentrations of bicarbonate-extractable P in soil (4.0, 4.1 mg P/kg), total P in pasture (0.9, 1.1 g P/kg), inorganic P in serum (1.0, 0.71 mmol P/L), and P in bone (73 mg P/mL) were all low. Although injectable and mineral salt supplements provided additional P in both outbreaks, these supplementary amounts were insufficient to prevent P deficiency. The P ingested by the cows from the pasture and supplements would have provided 20–55% of their daily P requirements of ~21 g P/d. Osteomalacia occurred in cattle at the 2 ranches as a result of severe P deficiency in the soil and forage, and inadequate P supplementation. Following diagnosis, control of P deficiency in beef cattle requires estimation of the amount of pasture P ingested and provision of sufficient additional supplementary P to meet the animals’ requirements.     

长期施用有机源土壤调理剂对果园土壤的影响-以草莓和苹果种植区为例

本文以北京市昌平区草莓和苹果种植区为研究对象,系统研究了2006-2019年长期施用有机源土壤调理剂对其不同土层深度中土壤容重、有机质等土壤理化指标的影响,并研究了不同测算模型对土壤有机碳及固碳量等结果的影响。结果表明：①长期施用有机源土壤调理剂显著提高了草莓和苹果种植区不同土层深度的容重和有机物含量(P<0.05)。②长期施用有机源土壤调理剂显著提高了草莓和苹果种植区有机碳的含量(P<0.05),其中草莓种植区的有机碳含量提高了89.58%,苹果种植区的有机碳含量提高了2.75倍。③不同测算模型对草莓和苹果种植区的有机碳和固碳量的结果存在差异。与实测法相比,基于估算法(IPCC,2006和Li等,2018)的有机碳储量和土壤固碳量结果较低。本研究结果可为有机源土壤调理剂改良果园土壤和固碳潜力提供提供方法和理论支持。