高等教育自学考试面向农村服务网络体系建设

高等教育自学考试面向农村延伸是农村社会、经济发展的迫切要求,服务网络体系建设是实现高等教育自学考试向农村延伸的有效途径。探讨了高等教育自学考试向农村延伸的运作方式和有效途径,即建立以市、县、乡三级网站为硬件支撑,充分发挥宣传、管理、服务功能,教材资料（含电视教学片）与助学辅导体系相配套,强化实践环节教学与技能培养为主要内容的高等教育自学考试面向农村的服务网络体系。     

橡胶园土壤酶活性与土壤肥力的关系

对海南省儋州市24个有代表性的橡胶园样地土壤酶活性与土壤肥力进行了研究。结果表明，不同胶园土壤酶活性存在很大不同，过氧化氢酶、蔗糖酶、酸性磷酸酶活性与土壤有机质、全氮和水解氮含量呈正相关关系，有的甚至达到极显著正相关；而多酚氧化酶和脲酶活性与土壤有机质，氮、磷、钾的有效性呈负相关。     

岩溶区土壤脲酶活性与土壤肥力的关系

为了讨论土壤脲酶活性作为岩溶区土壤肥力评价指标的可行性,笔者以重庆青木关岩溶槽谷地区为研究区,分秋、春、夏3个季节,采取10种不同土地利用方式下的土壤样品,分析土壤脲酶活性及土壤养分状况,并进行相关分析、通径分析和主成分分析。结果表明：研究区土壤脲酶活性与全氮和速效磷的相关水平极显著,同时与其他土壤养分相关。受到土壤养分的直接和间接影响,脲酶活性还可体现土壤有机质、全氮、水解氮的状况。因此,土壤脲酶活性可以在一定程度上反映岩溶区土壤的肥力水平。     

土壤微生物与土壤肥力的关系研究初探

通过对新疆沙漠荒漠区西南部低山丘陵区、中部绿洲区、北部盆地沙漠区三大不同生态环境土壤微生物分布特征及土壤理化性质的综合分析比较，得出土壤肥力与土壤微生物间呈正相关性（ｒ＝０．８１１３），可以根据土壤微生物对土壤肥力及状况进行判断。     

黄土丘陵区不同植被恢复模式对土壤酶活性的影响

为了解侵蚀环境下植被恢复对土壤酶活性的影响,以典型侵蚀环境黄土丘陵区纸坊沟流域生态恢复30a植被长期定位试验点为研究对象,选取坡耕地为参照,分析了植被恢复过程中土壤脲酶、磷酸酶、蔗糖酶、淀粉酶、纤维素酶、过氧化氢酶、多酚氧化酶及理化性质的演变特征。结果表明,黄土丘陵区的坡耕地由于不合理的人为干扰,土壤理化性质和酶活性较弱,通过植被恢复可以有效的改善土壤肥力,不同恢复模式对土壤酶活性和肥力的改善作用不同,恢复30a,脲酶活性增加33%~213%,磷酸酶活性增加275%~394%,蔗糖酶活性增加70%~210%,纤维素酶活性增加24%~48%,过氧化氢酶增加32%~96%,多酚氧化酶降低23%~29%,淀粉酶变化规律不同。不同植被恢复模式其生物特性不同,对土壤酶活性影响也不同。相关性分析说明磷酸酶、蔗糖酶、纤维素酶和多酚氧化酶与其它因子相关性相对较强,可以作为评价土壤质量的生物学指标。     

山东省粮田土壤有效硼分布及其与土壤肥力的关系

为了了解山东省典型地貌的农业粮田土壤中有效硼的时空分布,探索土壤有效硼与土壤肥力其他指标间的相关关系,为合理施用硼肥提供依据,对山东省17地市小麦-玉米轮作方式的耕层土壤样品的有效硼分析。结果表明,山东省农田土壤有效硼平均含量0.749 mg/kg,高于山东省土壤的平均水平;其变化范围为1.816~0.130 mg/kg;不同土壤类型土壤有效硼含量高低依次为潮土 > 褐土 > 砂姜黑土 > 棕壤;山东省不同的地貌类型土壤有效硼含量以黄泛平原区最高,鲁东丘陵区含量最低,鲁中山地丘陵区含量中等;通过土壤有效硼与土壤肥力指标的相关和逐步回归分析表明,土壤全氮对土壤有效硼的直接影响力最大,且为正效应;其次为土壤有机质,为负效应。具体原因有待于进一步研究。     

南疆膜下滴灌棉田土壤酶活性与土壤养分的关系

探讨土壤酶活性与土壤肥力质量指标的相关性,为棉田土壤质量评价提供生物学指标。以南疆棉田土壤为研究对象,测定棉田土壤养分含量和土壤酶活性,采用相关分析、通径分析和主成分等统计方法进行分析。土壤过氧化氢酶、酸性转化酶、碱性磷酸酶、脲酶与土壤有机质、全氮、速效磷达到极显著相关关系;通径分析表明,全氮和有机质含量是影响土壤酶活性的主要因子;有机质、全氮、过氧化氢酶、碱性磷酸酶是反映土壤肥力和质量的主要组分。用过氧化氢酶、酸性转化酶、碱性磷酸酶作为评价棉田土壤肥力水平的敏感生物指标具有可行性。     

宁南黄土丘陵区旱作苜蓿地土壤肥力特征分析

为了阐明宁南黄土丘陵区旱作苜蓿地土壤肥力的变化特征,采用算术均数赋值法将因子分析法、相关分析法、灰色关联法、变异系数法4种赋权方法相结合,对宁南半干旱黄土丘陵区旱作苜蓿地土壤肥力因子的权重进行计算。土壤肥力因子权重计算结果表明：研究区苜蓿地土壤肥力因子权重排序为有机质>速效氮>全量氮>土壤pH>速效磷≈全量磷>速效钾,土壤有机质、速效氮、全量氮、土壤pH的权重值相对较高,是该区旱作苜蓿地最为关键的肥力指标。利用改进的内梅罗综合指数法得到的苜蓿地土壤综合肥力指数在0.549~0.873之间,土壤肥力水平一般。退耕还林还草旱作苜蓿后,研究区水土流失明显得到控制,不同坡位苜蓿地土壤肥力指数差异逐渐减小;不同旱作年限苜蓿地土壤综合肥力指数排序为：7年生>3年生>19年生。     

沈阳东陵古松根区土壤磷酸酶活性与土壤养分的关系

从古松的纵向和横向研究了沈阳东陵不同深度古松土壤磷酸酶活性及与土壤养分（有机质、全氮、碱解氮、全磷、速效磷）的关系。结果表明：在距树干4m处可能是古松根系吸收养分较强的地方，土壤磷酸酶活性与土壤有机质、全氮、碱解氮和全磷都呈极显著的正相关，与速效磷呈极显著的负相关；磷酸酶可以表征古松根区土壤中磷素的含量状况；古松根区不同深度土壤中的磷酸酶活性可以作为评价土壤肥力指标之一。     

长期施肥对不同有机质含量农田黑土土壤酶活性及土壤肥力的影响

【研究目的】探讨长期施肥对不同有机质含量农田黑土酶活性及土壤肥力的影响,【方法】本研究以5种不同有机质含量农田黑土（梨树（SOM1.7）、德惠（SOM3）、海伦（SOM5）、嫩江（SOM6）、北安（SOM11））为研究对象,测定并分析了土壤脲酶、磷酸酶、蛋白酶、蔗糖酶的活性及土壤有机质、全氮、全磷、碱解氮、有效磷含量。【结果】结果表明,化肥的施用可不同程度提高农田黑土的养分含量及土壤酶的活性,其中北安(SOM11)提高的幅度最大,与其它四种土壤之间达到了差异显著水平（p<0.05）。相关分析结果显示：土壤脲酶、磷酸酶、蛋白酶、蔗糖酶与土壤有机质、全氮、全磷、碱解氮显著相关,土壤脲酶、蔗糖酶可以反映不同有机质含量农田黑土长期施肥后土壤质量变化趋势。     

Cassava yield loss in farmer fields was mainly caused by low soil fertility and suboptimal management practices in two provinces of the Democratic Republic of Congo

A better understanding of the factors that contribute to low cassava yields in farmers’ fields is required to guide the formulation of cassava intensification programs. Using a boundary line approach, we analysed the contribution of soil fertility, pest and disease infestation and farmers’ cultivation practices to the cassava yield gap in Kongo Central (KC) and Tshopo (TSH) provinces of the Democratic Republic of Congo. Data were obtained by monitoring 42 and 37 farmer-managed cassava fields during two cropping cycles in KC and one cropping cycle in TSH, respectively. Each field was visited three times over the cassava growing period for the observations. Logistic model was fitted against the observed maximum cassava root yields and used to calculate the achievable yield per field and for individual factor. At field level, the factor that led to the lowest achievable yield (Y_up(i)1) was considered as the dominant yield constraint. Cassava yield loss per field was expressed as the increase in the maximal root yield observed per province (Y_att- attainable yield) compared to Y_up(i)1. Y_att was 21 and 24 t ha⁻¹ in TSH and KC, respectively. With the cassava varieties that farmers are growing in the study areas, pests and diseases played a sparse role in the yield losses. Cassava mosaic was the only visible disease we observed and it was the dominant yield constraint in 3% and 12% of the fields in KC and TSH, respectively. The frequent yield constraints were suboptimal field management and low soil fertility. Cultivation practices and soil parameters led to Y_up(i)1 in 47% and 50% of the fields in KC, and in 47% and 41% of those in TSH, respectively. Individual soil parameters were the yield constraint in few fields, suggesting that large-scale programs in terms of lime application or recommendation of the blanket fertilisers would result in sparse efficacy. In KC, yield losses caused by low soil fertility averaged 6.2 t ha⁻¹ and were higher than those caused by suboptimal field management (5.5 t ha⁻¹); almost nil for cassava mosaic disease (CMD). In TSH, yield losses caused by low soil fertility (4.5 t ha⁻¹) were lower than those caused by suboptimal field management (6.5 t ha⁻¹) and CMD (6.1 t ha⁻¹). Irrespective of the constraint type, yield loss per field was up to 48% and 64% of the Y_att in KC and TSH, respectively. Scenario analysis indicated that the yield losses would remain at about two third of these levels while the dominant constraint was only overcome. We concluded that integrated and site-specific management practices are needed to close the cassava yield gap and maximize the efficacy of cassava intensification programs.     

Relationships between soil fertility,herbage quality and manure composition on grassland-based dairy farms

It is reasonable to expect that compliance with grassland fertilization recommendations in the long run results in optimal soil fertility, and subsequent herbage quality. Here, we evaluate the development of soil, herbage and manure characteristics and their relation over the last decades. We hypothesized that herbage and manure quality are related with soil fertility. We used a large database with results of soil tests, spring forage quality characteristics, and manure analyses, which were made on demand of dairy farmers. We considered the Netherlands as a whole and three selected regions with contrasting soil types (sandy soil, riverine clay, and peaty marine clay). Effects of soil fertility on herbage quality were evident when comparing farms. Farms higher in soil P and K generally have correspondingly higher contents in forage. On average, soil fertility and herbage characteristics were within or just above the agronomical optimal range during the last decades. Herbage crude protein content decreased in all regions during last two decades, which is likely an effect of legislative measures on decreasing the application of N. Selenium (Se) and sulphur (S) contents increased sharply on sandy soils, likely because of increased use of Se and S containing fertilizers. Manure composition did not differ between soil types. In conclusion, at farm level, the element composition of herbage reflected the soil fertility status. The contents of S, P, K, Na, Mg, and Ca in the herbage were all significantly influenced by soil fertility characteristics. Our results emphasize the importance of maintaining soil fertility for high quality roughage production.     

Organic amendment and minimum tillage in winter wheat grown in Mediterranean conditions: Effects on yield performance,soil fertility and environmental impact

The experiment was conducted to evaluate the agronomic benefit of the application of organic fertilizers combined with different soil tillage on quantitative and qualitative components of winter wheat (Triticum durum Desf., cv. ‘Simeto’) and on chemical soil fertility parameters. The environmental impact, due to heavy metals introduced in soil-plant system, was further investigated. Soil tillage treatments consisted of conventional (CT) and minimum tillage (MT). Fertilization treatments were: mineral at 100 kg N ha⁻¹ (N_min); municipal solid waste compost at 100 kg N ha⁻¹ (N_comp); 50 kg N ha⁻¹ of both compost and mineral fertilizers (N_mix); sewage sludge at 100 kg N ha⁻¹ (N_ss). These treatments were compared with an unfertilized control (N₀). No significant difference was observed between the two soil tillage treatments for quantitative yield production, while among the fertilization treatments N_ss did not show any significant difference compared to N_min. At the end of the research, the fertility of the soil (oxidable carbon, total nitrogen, available phosphorus) was on average higher in N_comp and N_ss treatments compared to the N₀ and N_min ones. The overall distribution of heavy metals in soil-plant system respect to the different fertilizer treatments has not allowed to grouped their effects with Principal Components Analysis. This result showed that the amount of potential pollutants applied by organic amendments did not modified the dynamic equilibrium of the soil–plant system. The MT, as well as the fertilization with the application of sewage sludge (N_ss), allowed to reach productive performance similar to conventional management (CT with N_min). Here we demonstrate that, in the short term period, sustainable agronomical techniques can replace the conventional one with environmental benefit.     

小麦冠层结构与产量及其构成因素的典范相关分析

选用２０个小麦品种（系）,采用典范相关分析方法,分析了小麦冠层结构与产量及其构成因素的相关性。结果表明,产量与其构成因素和植株特性呈显著相关,穗粒数和穗数对产量和单株产量的贡献均较大,干物重和株高对产量的贡献最大;叶长与产量呈显著相关,倒三叶长对产量的影响最大,对单株产量的影响３片叶相近;茎壁厚、节间长与单株产量呈显著相关。产量构成因素与各冠层结构特性均存在显著的典范相关。茎壁厚和节间长与茎粗均相关显著;在叶片特性中,除叶宽与披垂度相关不显著外,其余各组性状间均相关显著。     

苏丹草对土壤中菲、芘修复作用的研究

采用盆栽试验法,研究苏丹草对土壤中菲、芘的去除效果,及土壤菲、芘残留量与多酚氧化酶和脲酶活性之间的关系。结果显示,在菲、芘去除中,植物-微生物联合修复起到了主要作用,50d试验完成后,去除率分别达到了68.9%和71.24%;对酶活性与菲、芘残留量进行相关性分析得出,当酶的活性高时,对菲、芘的去除率也增高;种植植物可以增加微生物酶的活性,从而提高菲芘去除率,较无植物处理分别增高了51.7%和55.54%。说明植物-微生物联合修复可以作为多环芳烃修复的一种主要途径,并且也可用脲酶的活性作为土壤中菲、芘污染生态毒理指标。     

转抗旱基因棉对土壤酶活性及速效养分含量的影响

旨在探究不同生育期内种植转抗旱基因棉及其常规棉对土壤酶活性及速效养分含量的影响。应用化学分析法和溶剂浸提法对2种棉花的土壤酶活性和速效养分含量进行比较分析。结果表明,在苗期,转抗旱基因棉土壤速效磷含量显著低于其常规棉,而土壤铵态氮、硝态氮含量和脲酶活性则显著高于其常规棉,其余4个生育期它们的含量与活性均无显著差异,土壤碱性磷酸酶和过氧化氢酶活性5个生育期差异均不显著。对土壤酶活性和土壤速效养分含量的相关性分析表明,土壤铵态氮含量与土壤脲酶活性呈显著正相关,而与土壤碱性磷酸酶活性呈显著负相关;土壤速效磷与土壤全氮呈极显著负相关;土壤硝态氮含量与土壤碱性磷酸酶活性呈显著负相关,与土壤铵态氮含量显著正相关。综上,转抗旱基因棉花的种植几乎并不影响土壤速效养分含量及土壤酶活性,但随着生育期的不同其土壤速效养分含量及土壤酶活性也不同。     

沟垄覆膜对连作马铃薯土壤酶活性、理化性状及产量的影响

以当地主栽品种“新大坪”为试验材料,采用大田定位试验,研究了平畦不覆膜(CK)、平畦覆膜(T1)、全膜垄播(T2)、全膜沟播(T3)、半膜垄播(T4)、半膜沟播(T5) 6 种栽培模式对连作马铃薯土壤酶活性、理化性状及产量的影响。结果表明,沟垄覆膜栽培可不同程度提高马铃薯连作田土壤过氧化氢酶、脲酶、碱性磷酸酶的活性,其中 T2 对 3 种酶活性的提高效果最为显著;沟垄覆膜可降低土壤 pH,从而改善马铃薯根际土壤的理化性状,且以 T2 对土壤化学性质的改善最为明显,沟垄覆膜可不同程度提高土壤电导率;此外,沟垄覆膜栽培还可以显著提高马铃薯块茎的产量,其中T2 增产幅度最高可达 75%。本研究以期为半干旱地区马铃薯连作障碍的克服及提高马铃薯产量提供理论依据。     

不同种植密度对小麦根际土壤微生物数量及土壤酶活性的影响

研究了不同种植密度对小麦豫麦49-198根际土壤微生物数量及土壤酶活性的影响,结果表明,根际土壤细菌在拔节和抽穗期数量较多,而放线菌、真菌在开花期数量最多。根际细菌数量、放线菌数量及土壤蛋白酶活性、脲酶活性随着群体密度的增加呈单峰曲线变化,以基本苗150×104株/hm2或225×104株/hm2处理最高;真菌数量则随密度的增加而减少。随着种植密度的增加,微生物数量及酶活性与产量的变化趋势相一致,表明微生物和酶活性增加一定程度上有助于提高作物产量。