覆盖方式对浙西低丘橘园土壤碳库和养分流失的影响

设置了对照(清园)、秸秆覆盖、自然生草和人工种草4个处理,比较了不同覆盖方式对丘陵红壤区柑橘土壤有机质、养分、水分、地表径流量、地表径流中泥沙和养分流失量以及柑橘产量和品质等的影响,以期为南方果园科学管理提供依据。结果表明:3种不同处理方式促进了表土不同形态的有机质积累,提高了水稳定性团聚体含量和土壤水分贮量并降低了表层的土壤容重。3种覆盖方式的综合效果以秸秆覆盖最佳,秸秆覆盖后的土壤碳库管理指数较对照提高了55.00%,年累计径流量、泥沙流失量、全氮和全磷流失量较对照分别降低了61.27%、89.31%、79.24%和87.50%。秸秆覆盖处理可小幅提高柑橘产量,显著提高柑橘的糖度,降低其可滴定酸含量。综上所述,低丘果园行间覆盖农作物秸秆具有良好的生态效应,能够有效减少养分流失,改善土壤理化性质和生态环境,可作为南方丘陵果园生态优化的水保措施。

贵州省第四纪红黏土发育土壤的性状及其系统分类研究

为了解碳酸盐岩分布区第四纪红黏土发育土壤的特性,以贵州省作为样区,通过路线考察和典型剖面的采样分析,对其风化成土特点及土壤类型进行了研究。结果表明,贵州省第四纪红黏土的厚度明显高于我国东南地区第四纪红黏土的,但其风化及红化程度低于后者的。研究认为贵州省第四纪红黏土不完全是由碳酸盐岩直接风化形成的,是周边山体提供物源多次反复堆积形成的。根据中国土壤系统分类的诊断标准,可把贵州省第四纪红黏土发育的土壤划分为富铁土、淋溶土和雏形土3个土纲,下分6个亚纲、11个土类和14个亚类。

水田改果园后土壤形态及性状的演变

近年来,水田改作经济林在中国南方地区非常普遍,为深入了解这一土地利用的转变对土壤质量的影响,选择浙江省杭州市由水田改果园时间系列的代表性土壤剖面,采集分层土壤样品,采用田间调查与室内分析相结合的方法对比分析了水田改果园后土壤形态及性质的变化。结果表明:水田改果园20年的土壤与长期植稻的水田土壤相比,地下水位下降了20 cm,耕作层土壤容重增加了28.0%,坚实度增加了2.65倍;耕作层和犁底层土壤颜色亮度和彩度增加,铁锈斑纹等新生体减少;耕作层土壤pH值降低,土壤有机质、全氮和碱解氮含量分别下降了42.1%、40.3%和37.4%,土壤全磷、有效磷和速效钾含量分别增加了1.35、15.62倍和3.07倍;耕作层土壤微生物生物量碳和生物量氮分别减少了76.5%和52.1%;好氧细菌与厌氧细菌比值增加了97.0%,革兰氏阴性细菌与革兰氏阳性细菌比值降低了24.6%。研究表明,水田改果园后,土壤形态和性状发生显著变化,并对土壤生态环境带来显著影响。

适度深耕配施有机肥减少蔬菜对土壤重金属的吸收

为了解常规农业措施在污染农田安全利用实施中的效果,选择轻度和中度2种重金属污染农田,分别开展了3种耕作深度(20、30和40 cm)与2个有机肥施用水平(0、30 t/hm^2)的不同组合试验,探讨了深耕对土壤剖面中重金属分布与蔬菜吸收土壤重金属的影响。结果表明,深耕(30、40 cm)可显著稀释0~20 cm土壤重金属水平,减少蔬菜吸收土壤中的重金属,降低效果随耕作深度的增加而增强。深耕后,轻度污染土壤上生长的蔬菜中重金属含量都在标准值以下;但中度污染土壤上生长的蔬菜中部分重金属仍存在超标现象;在深耕同时,增施凹凸棒石+石灰混合改良剂可降低土壤中重金属的生物有效性,显著降低蔬菜对中度污染土壤中重金属的吸收。研究也发现,深耕后0~20 cm土层土壤有机质和全氮、有效磷、有效钾含量也因稀释而下降,并导致蔬菜生物量的下降,但配施有机肥可减轻因深耕引起的副作用。研究认为,适度深耕配施有机肥适用于轻度污染土壤的修复,用于中度污染土壤修复时还需要适当增施化学改良剂。

肥料与调理剂配施对新垦红壤性状综合改良及大豆产量的影响

通过田间小区试验,探讨了化肥、有机肥、石灰石粉、结构改良剂配合施用对新垦红壤性状综合改良的效果以及对大豆产量的影响。试验结果表明:与对照相比,对土壤质量综合提升和大豆生长效果最佳的处理为石灰石粉+化肥-有机肥配合施用+结构改良剂,其次为石灰石粉+化肥-有机肥配合施用;化肥-有机肥配合施用的效果好于单施化肥或单施有机肥的效果;石灰石粉+单施有机肥处理的改土效果好于石灰石粉+化肥处理的效果,但对作物生长的效果略差于石灰石粉+化肥处理的效果。

Spatial and temporal variation of nitrogen exported by runoff from sandy agricultural soils

The eutrophication problem has drawn attention to nutrient leaching from agricultural soils, and an understanding of spatial and temporal variability is needed to develop decision-making tools. Thus, eleven sites were selected to monitor, over a two-year period, spatial and temporal variation of runoff discharge and various forms of N in surface runoff in sandy agricultural soils. Factors influencing the variation of runoff discharge and various forms of N in surface runoff were analyzed. Variation of annual rainfall was small among 11 sites, especially between 2001 and 2002. However, variation of annual discharge was significant among the sites. The results suggest that rainfall patterns and land use had significant effect on discharge. The concentrations of total N, total kjeldahl N （TKN）, organic matter-associated N （OM-N）, NO3- -N, and NHn＋-N in the runoff ranged widely from 0.25 to 54.1, 0.15 to 20.3, 0.00 to 14.6, 0.00 to 45.3, and 0.00 to 19.7 mg/L, respectively. Spatial and temporal variations in the N concentration and runoff discharge were noted among the different sites. Annual loads of N in the runoff varied widely among monitoring sites and depend mainly on runoff discharge. High loads of total N, OM-N, NO3--N, and NHn＋-N in the runoff either in citrus groves or on vegetable farms occurred from June to October for each year, which coincided with the rainy season in the region. This study found that N in surface runoff was related to rainfall intensity, soil N level, and fertilizer use.

Effects of Soil Properties on Phosphorus Subsurface Migration in Sandy Soils

The soil factors influencing the potential migration of dissolved and particulate phosphorus(P) from structurally-weak sandy subsoils were evaluated by means of soil column leaching experiments. Soil colloids were extracted from two types of soils to make the colloid-bound forms of P solution. Eight sandy soils with diverse properties were collected for packing soil columns. The effects of influent solutions varying in concentrations of colloids,P,and electrolyte,on the transport of P and quality of leachates were characterized. P migration in the soils was soil property-dependent. High soil electrical conductivity values retarded the mobility of colloids and transportability of colloid-associated P(particulate P) . Soil electrical conductivity was negatively correlated with colloids and reactive particulate P(RPP) concentrations in the leachates,whereas,the total reactive P(TRP) and dissolved reactive P(DRP) concentrations in the leachates were mainly controlled by the P adsorption capacity and the P levels in the subsoil. The reactive particulate P in the leachates was positively correlated with the colloidal concentration. Increased colloidal concentration in the influent could significantly increase the colloidal concentration in the leachates. Elevated P concentration in the influent had little effect on P recovery in the leachates,but it resulted in significant increases in the absolute P concentration in the leachates.

Extractability and Mobility of Copper and Zinc Accumulated in Sandy Soils

Extractability and mobility of Cu and Zn and their relationships with 1) accumulation of Cu and Zn and 2) soil pH were studied in three sandy soils (Wabasso, Ankona, and Winder) from commercial citrus groves in Florida, USA. The soils, with a broad range of Cu and Zn concentrations, were fractionated by a modified procedure of Amacher, while Cu and Zn mobility were evaluated using column leaching. The extractability of Cu and Zn increased with decreasing soil pH. Also with increasing total soil Cu and Zn for extractable Cu in the Wabasso sand a threshold level, where the metal extraction rate increased, was noted at 100 mg kg-1, whereas for extractable Zn in the Wabasso sand the threshold level was found at 60 mg kg-1 and in the Ankona sand at 120 mg kg-1. These results suggested that the release potential of Cu and Zn was greater in the Wabasso sand than in the Ankona sand. The column leaching experiment showed that at total soil Cu or Zn concentrations < 100 mg kg-1 all leachates had low Cu and Zn concentrations. However at total concentrations > 200 mg kg-1 for Cu and > 150 mg kg-1 for Zn with decreasing soil pH, the concentrations of both Cu and Zn in the leachates increased exponentially. Also in these sandy soils soluble Cu and Zn mainly originated from the exchangeable fractions, and pH was a key factor controlling Cu and Zn extractability and mobility.

Effect of Compost Amendment on Heavy Metals, Nitrogen and Phosphorus in a Peat-Based Container Medium

A laboratory study was conducted to evaluate the effect of compost amendment on mobility and leaching potential of heavy metals, nitrogen (N) and phosphorus (P) from a peat-based commercial container medium containing 700 g kg-1 peat, 200 g kg-1 perlite and 100 g kg-1 vermiculite at varying amendment rates of compost (0, 0.25, 0.50, 0.75 and 1.00 L L-1). Increasing compost amendment significantly and linearly increased the pH (P < 0.01), the total concentrations of organic carbon (P < 0.05), copper (Cu) (P < 0.01), cadmium (Cd) (P < 0.01), and lead (Pb) (P < 0.01), and increased the bulk density (P < 0.01) of the medium. The electrical conductivity (EC), and total N and P of the medium increased significantly (P < 0.01) and quadratically with increasing compost amendment. The relationship of the C/N ratio of the medium with the compost amendment rate was decreasing, significant (P < 0.01) and cubic, while that of the total Zn was increasing, significant (P < 0.01) and cubic. Extractable P, NO3-N, and NH4-N increased initially with an increasing compost amendment of up to 0.50 L L-1 and then decreased with further increasing compost rate. Increasing compost rates resulted in a highly significant (P < 0.01) and linear increase in total Cd, Cu, and Pb, and a highly significant (P < 0.01) and cubic increase in total Zn in the medium. Increasing compost rates also significantly (P < 0.01) increased extractable Cu (linearly) and Zn (quadratically), but significantly (P < 0.01) decreased extractable Pb (linearly). There was no significant effect of compost amendment on the extractable Cd concentration in the medium. However, with increasing compost rates from 0.25 to 1.00 L L-1, extractability of P, Cd, Cu, Pb and Zn (extractable concentration as a percent of total) was decreased, indicating that compost amendment could lower the leachability of these elements from the medium.

Simulation study on copper and zinc release from contaminated sandy soils due to acidification

在砂质土的造林能引起土壤使发酸并且影响 Cu andZn 版本。Cu 和 Zn 的行为免除污染可耕的砂质土我们在有土壤的模仿的使发酸的方法的实验室的 reinvestigated。结果证明土壤使发酸能在土壤改变 Cu 和 Zn 的化学形式，从碳酸盐推动 Cu 和 Zn 的转变联系部分到可交换，有机物和氧化物联系了部分，并且因此在土壤增加 Cu 和 Zn 的版本潜力。沥滤的 Zn 上的使发酸的 Theeffect 比 Cu 的更重要。在土壤的水溶解度 ofCu 和 Zn 与减少的 pH 被增加，并且 Cu 和 Zn 的溶解度分别地在 pH 3.8-4.5，和 6.2-6.5 指数地被增加。

绿肥配施有机肥改良新建红壤橘园的效果研究

为探索亚热带低丘新建果园土壤肥力快速提升方法,在浙西选择一新建红壤橘园,进行了为期2年的种植绿肥与联合施用有机肥的土壤培肥试验。试验设对照、双季绿肥、有机肥及双季绿肥+有机肥等4个处理,各处理化肥用量相同。试验结果表明,从土壤有机碳、微生物生物量碳、速效氮磷钾、酶活性及土壤容重和水稳定性团聚体等肥力指标的变化来看,培肥效果:双季绿肥+有机肥>有机肥>双季绿肥。在不施用有机肥的条件下,种植绿肥后土壤有机碳、微生物生物量碳、有效磷、速效钾、水稳定性团聚体分别比对照增加13.14%、52.00%、27.08%、18.91%、20.25%,土壤容重下降2.90%,但增幅相对较小;土壤有效态微量元素含量几乎没有变化。在种植绿肥的同时施用有机肥可显著增加土壤有机碳、微生物生物量碳、有效磷、速效钾、水稳定性团聚体,分别比对照增加94.46%、276.00%、94.41%、110.81%、86.27%,土壤容重下降9.42%;同时可明显增加土壤全磷和微量元素的含量,全磷、有效态硼、钼、铜、锌水平分别比对照增加27.27%、266.67%、72.73%、155.56%、168.18%。种植绿肥同时施用有机肥的紫云英和黑麦草生物量分别为种植绿肥的1.62~1.90和1.79~1.95倍。分析认为,由于新建红壤果园肥力低下,仅靠种植绿肥等生草技术对土壤肥力的提升有限;施用有机肥和种植绿肥方式相结合是新建红壤果园的快速培肥途径。

梵净山垂直带土壤的发生学特性与系统分类研究

为了解贵州东北部山地土壤的发生学特性及土壤分布,选择梵净山地区采集了不同海拔高度的13个代表性土壤剖面,分析了其成土环境、土壤风化强度的垂直变化,鉴定了区内土壤的主要诊断层、诊断特性,并根据中国土壤系统分类对研究区土壤类型进行了分类。结果表明,随着海拔的增加,区内土壤温度状况由热性转变为温性,水分状况逐渐由湿润向常湿润转变。梵净山地区土壤风化较弱,土壤中存在较多的2∶1型矿物,土壤脱硅富铁铝化处于中下水平。土体厚度、土壤黏粒、全铁、游离氧化铁含量、铁游离度随海拔增加而下降,砾石含量、黏粒CEC、土壤ba值、黏粒Sa值随海拔增加而上升,部分土壤出现明显的黏化。区内土壤酸化明显,多数土壤的pH在5.5以下,部分土壤的铝饱和度超过了60%,土壤的平均铝饱和度随海拔增加而下降。研究区土壤黄化非常明显,土壤色调主要为10YR。共检出淋溶土、雏形土和新成土3个土纲,5个亚纲、8个土类和12个亚类,土壤类型主要由淋溶土和雏形土组成。亚纲在海拔高度变化上有一定的分布规律,随着海拔的上升,由湿润淋溶土、湿润雏形土向常湿淋溶土、常湿雏形土转变。

历史时期宁绍平原稻作环境与现代水耕人为土的形成

通过分析宁绍平原形成、水利建设、人口变化及古代粮食种植业与农业技术发展等的历史,探讨了该平原水耕人为土形成过程。分析认为,宁绍平原地区水稻种植虽然已有7000 a以上的历史,但现代水耕人为土大约起于西汉之后,形成时间不足2000 a,在唐宋、明清和20世纪50～70年代有较快速的发展;水耕人为土形成大概可划分为5个时期。最早的水稻种植区为平原与丘陵山地过渡区的洪积扇上,水网平原区大规模水稻种植主要在唐宋之后,多数成土时间约1000 a左右;滨海平原区种植水稻时间较短,多数在500 a之内。研究认为,水分环境改善、农作技术发展和人口增加是宁绍平原水耕人为土形成、发展和演变的主要动力。

水耕时间对低丘水田土壤发育的影响

【目的】了解水耕时间对亚热带低丘水田土壤性态的影响,对水耕土壤进行正确分类。【方法】在浙江省金衢盆地内选择坡麓和岗地二种地貌单元,观测不同水耕时间的第四纪红土发育水田土壤的剖面形态特征,分层采集土样分析土壤理化性状。【结果】随着水耕时间的增加,土壤颜色由红转黄,色调由2.5YR向7.5YR或10YR演变;表层土壤黏粒含量逐渐下降,有机质与全磷及有效磷积累,pH、阳离子交换量和活性铁逐渐增加,土壤游离氧化铁逐渐下移淀积;水耕时间对土壤性状的影响由表层向心土层发展。调查表明,由于水分条件的差异,水耕时间对坡麓地带水田土壤性状的影响大于岗地水田。【结论】由第四纪红土旱地改为水田,形成典型水耕人为土约15 a,形成铁聚水耕人为土约150 a以上,水耕时间低于150 a主要形成简育水耕人为土;随着水稻种植时间的增加,活性有机质占有机质的比例随有机质积累同步增加,水稻土心土层具有较强的固碳潜力。

贵州雷公山土壤发生学性状的垂直变化特征研究

为了解我国亚热带山地土壤发生学性状随海拔的垂直变化特点,选择位于亚热带常湿润气候区的贵州省雷公山作为研究对象,调查与采样分析了不同海拔高度的17个土壤剖面的理化性状及其与海拔的关系。结果表明,雷公山土壤的众多发生学性状与海拔高度存在显著的相关,随着海拔的升高,呈现土壤矿物质风化减弱而有机质和养分积累增强的变化趋势。表土层厚度、砾石、有机质、全氮和全磷含量、腐殖质的H/F比,土壤粉砂含量、粉黏比、CEC、ba值、氧化铁活化度、黏粒Sa值、黏粒矿物中蛭石和云母相对比例均随海拔的升高而增加;而土体厚度、表土胡敏酸比值、土壤黏粒含量、游离氧化铁含量、氧化铁游离度和黏粒矿物中高岭石相对比例则随海拔升高而下降。研究土壤酸化明显,pH和盐基饱和度普遍较低,随海拔升高的变化趋势不明显。研究认为,雷公山地区土壤发生学性状主要受现代成土环境影响,随海拔变化的温度可能是控制这一地区土壤空间变异的主要因素。区内土壤主要发生学性状随海拔升高呈波动状变化,多数发生学性状具有协同变化的特征;不同地理发生学分类土壤带间发生学性状存在一定的差异。根据中国土壤系统分类,研究区土壤类型主要为淋溶土和雏形土,二者也不存在海拔上的明显分界,而呈现复合分布。

地形部位对亚热带低丘梯田土壤性态与类型的影响

【目的】为了解地形对亚热带丘陵地区稻田土壤发生与演变的影响。【方法】在浙江省衢州市和杭州市分别选择了由第四纪红土和凝灰岩风化物等2类母质发育的地形系列梯田,比较分析了岗背、高坡、缓坡和坡麓等不同地形部位梯田土壤剖面发生学性状及土壤类型的差异。【结果】结果表明,由岗背经高坡、缓坡至坡麓,土壤受耕作熟化影响(包括颜色变化、酸度下降)的程度逐渐加深,土体厚度、氧化还原层厚度和铁锰新生体数量、剖面中黏粒和氧化铁含量的垂直分异呈增加的趋势,同时表土有机碳、全氮、全磷、有效磷的积累也呈现增加趋势。调查表明,2类母质发育的土壤中位于坡麓地带的梯田土壤剖面氧化铁垂直迁移显著,土壤类型属铁聚水耕人为土;岗背和高坡部分的梯田土壤剖面发育相对较弱,形成的为简育水耕人为土;缓坡地梯田中可发生铁的渗移,形成的土壤或为铁渗水耕人为土或为简育水耕人为土。【结论】研究认为,地形部分可通过改变土壤剖面中水分状况和运移影响亚热带低丘陵地区水耕人为土的发育。