Soil acidification induced by intensive agricultural use depending on climate

Journal of Soils and Sediments - Soil acidification is a major issue in agricultural ecosystems. However, how agricultural land uses shape the soil pH pattern and affect soil acidification on a...     

长期复种绿肥下光合碳在水稻-土壤系统中的分配与稳定

冬季复种绿肥是我国南方稻区传统的培肥增产模式,探究长期冬种绿肥下光合碳在水稻-土壤系统中的分配规律,对深入解析稻田土壤碳循环、充分发挥绿肥的生态功能具有重要意义。基于稻-稻-绿肥复种长期定位试验（38年）,针对稻-稻-紫云英、稻-稻-油菜和稻-稻-休闲三种处理,采用13C-CO2脉冲标记技术,研究长期冬季复种绿肥下光合碳在早稻季分蘖期水稻-土壤系统中的分配特征。结果表明,与冬季休闲处理相比,复种紫云英和油菜处理使早稻地上部13C-光合碳积累量每穴分别增加19.9 mg和80.6 mg;复种紫云英处理使早稻地下部13C-光合碳积累量每穴降低2.7 mg,而复种油菜处理对早稻地下部13C-光合碳积累量无显著影响。同时,冬季复种紫云英和油菜减少了早稻13C-光合碳向土壤的分配,积累量每穴分别降低7.6 mg和7.8 mg;复种紫云英处理对水稻13C-光合碳在土壤颗粒有机碳（POC）和矿物结合态有机碳的分配比例无显著影响,复种油菜处理促进了水稻13C-光合碳向土壤POC中的分配,使13C-POC的占比增加35.3%。综上,长期复种绿肥促进了水稻分蘖期光合碳在水稻-土壤系统中的积累,与冬季休闲处理相比,冬季复种绿肥使光合碳在水稻-土壤系统中积累量增加3.7%~28.0%;增加了光合碳向水稻地上部的分配,减少了其向水稻地下部及土壤中的分配比例;且复种油菜处理减弱了土壤中水稻光合碳的稳定性;从增加有机碳总量和光合碳稳定性的角度可知,复种紫云英是相对较好的一种冬季复种绿肥模式。     

基于探地雷达的喀斯特峰丛洼地土壤深度和分布探测

[目的]研究喀斯特土壤的深度和分布,为利用探地雷达(GPR)技术开展喀斯特地区峰丛洼地土壤分布的研究提供理论依据。[方法]通过室内模拟试验,建立喀斯特地区3种典型质地土壤(砂质黏壤土、黏壤土、粉(砂)质黏土)中探地雷达电磁波波速和土壤含水量的关系式。通过实地测定土壤质地和含水量,选择合适的关系式,对探地雷达图像进行校准、解译,获得土壤深度,并采用开挖法进行验证。[结果]得到了3种质地土壤中电磁波波速(ν)与含水量(θ)关系的三次多项式。利用该关系式探测的喀斯特土壤理论深度与实地开挖的结果相符,误差为0—10cm。利用探地雷达软件生成了反映测线下不同位置土壤深度的二维图像和样方内土壤深度分布的三维图像,表明土壤主要分布在0—50cm。[结论]利用探地雷达技术探测喀斯特地区土壤深度和分布是切实可行的。     

Effect of nitrogen fertilization on the fate of rice residue-C in paddy soil depending on depth: <Superscript>13</Superscript>C amino sugar analysis

A 100-day incubation experiment was conducted to (i) trace the fate of rice residue-derived ¹³C in the amino sugar (AS) pool in 0–1-cm (oxic) and 1–5-cm (anoxic) layers of paddy soil and (ii) evaluate the effects of inorganic N ((NH₄)₂SO₄) fertilization on the formation of AS at early and late incubation times (5 and 100 days, respectively). The accumulation of rice residue-derived AS occurred at 5 and 100 days in both soil layers as a result of AS stabilization. Inorganic N addition increased the contents of rice residue-derived muramic acid, glucosamine, and galactosamine in the 0–1-cm soil layer for both incubation times by average on 14.7–20.8%, 23.7–31.8%, and 11.6–23.3%, respectively. In contrast, no effects of N fertilization on AS content in the 1–5-cm soil layer were found. The amount of rice residue-derived AS was higher in the 1–5-cm than in the 0–1-cm soil layer at early incubation time, probably due to the higher contents of ammonium here compared to the upmost oxic layer where nitrate was the dominated N form. Thus, the preferential uptake of ammonium but not nitrate by microorganisms led to the higher formation of rice residue-derived AS in the anoxic soil layer. The ratio of fungal to bacterial residues (fungal glucosamine/muramic acid) ranged between 1.0 and 1.7 for rice residue-derived AS and was 12.5–14.6 for total AS, indicating that fungi and bacteria have similar contributions to the decomposition of fresh rice residue whereas native soil organic matter (SOM) is a fungi-predominated process. This study emphasized that coupling of C and N cycles in paddy soils is different in oxic and anoxic layers, resulting in variation of plant residue decomposition and formation of SOM.     

奶山羊乳房炎防治关键技术

富平县是中国奶山羊之乡,羊乳之都,千亿级奶山羊产业链的主战场。全县奶山羊存栏 82 万只,全县 16 个镇（街道办）都有养殖,其中 主要集中在刘集镇、流曲镇、齐村镇、到贤镇、东华街道办、 留古镇等。全县乳品加工企业 6 家,为奶山羊产业提供了强有力的支撑。随着奶 山羊产业链的不断延伸和升级,奶山羊存栏量不断上升。由于存栏的增加,奶山羊乳房炎发病数较多,对产业影响较大。为了做到“早发现、 早治疗、早处置、早预防”奶山羊乳房炎,笔者就奶山羊乳房炎的发生机理和防治技术做了临床研究,取得了较好的防治效果,现分享如下。     

大白菜新品种潍春白1号的选育

潍春白1号是利用自交不亲和系BZ-07和自交不亲和系BZ-09配制而成的早熟春大白菜一代杂种。生育期63d(天)左右,植株矮桩直筒形,株高35cm,开展度48cm;叶色深绿,叶柄白,叶片较薄,叶面平展,外叶7～8片;叶球合抱炮弹形,球高32cm,横径24cm,球形指数1.33,球叶淡黄色,36片左右,单球质量1.7kg;不易先期抽薹,平均短缩茎长3.3cm;净菜率76.5%,软叶率44.5%,干物质含量4.95%,VC220.00mg.kg-1,可溶性糖1.53%,蛋白质1.18%,粗纤维0.55%,品质佳;对病毒病、霜霉病和软腐病的抗性均优于对照鲁春白1号,中抗TuMV。平均每667m2净菜产量4365kg,适宜保护地、早春反季节及高寒地区秋早熟栽培。