江苏省土壤有机质含量时空变异特征及驱动力研究

土壤有机质(SOM)含量是估算土壤碳储量、评价土壤肥力的重要指标,研究SOM时空演变对评估区域土壤固碳潜力,实现土壤可持续利用具有重要意义。以江苏省为例,利用全国第二次土壤普查资料和2006年采样数据,基于地统计学方法和GIS技术,对比研究了1980 - 2006年全省范围内表层(0 ~ 20 cm)SOM含量的时空变异特征及其驱动因子。结果表明：1980年和2006年江苏省SOM平均含量分别为16.55 ± 8.50 g kg^-1和18.31 ± 8.32 g kg^-1,变异系数分别为51.36%和45.44%。两个时期SOM的变异函数均符合指数模型,块金系数由51.85%增加为56.52%,变程由71.55 km减少至37.83 km,SOM含量的空间自相关性减弱,自相关距离减小。1980-2006年,SOM含量空间分布呈现出北增南减,沿江平原增,宁镇丘陵减,滨海平原基本持平的空间格局,增加幅度由北向南逐渐减小。SOM含量的初始值影响其空间格局的演变,总体上呈现初始SOM含量的高值降低、低值增加的趋势。肥料的大量使用在提高粮食产量的同时也增加了作物残茬和根系的生物量;秸秆还田的大力推行,使得大量的有机物质进入土壤,促进了SOM的累积。不同的土地利用变化对SOM含量变化的作用不同,土地利用方式转变成水田、旱地和林地促进了SOM的增加,而转变成荒地后导致SOM含量下降。     

Rhizosphere priming of soil organic matter by bacterial groups in a grassland soil

Plants often impact the rate of native soil organic matter turnover through root interactions with soil organisms; however the role of root-microbial interactions in mediation of the “priming effect” is not well understood. We examined the effects of living plant roots and N fertilization on belowground C dynamics in a California annual grassland soil (Haploxeralf) during a two-year greenhouse study. The fate of ¹³C-labeled belowground C (roots and organic matter) was followed under planted (Avena barbata) and unplanted conditions, and with and without supplemental N (20 kg N ha⁻¹ season⁻¹) over two periods of plant growth, each followed by a dry, fallow period of 120 d. Turnover of belowground ¹³C SOM was followed using ¹³C-phospholipid fatty acid (PLFA) biomarkers. Living roots increased the turnover and loss of belowground ¹³C compared with unplanted soils. Planted soils had 20% less belowground ¹³C present than in unplanted soils after 2 cycles of planting and fallow. After 2 treatment cycles, unlabeled soil C was 4.8% higher in planted soils than unplanted. The addition of N to soils decreased the turnover of enriched belowground ¹³C during the first treatment season in both planted and unplanted soils, however no effect of N was observed thereafter. Our findings suggest that A. barbata may increase soil C levels over time because root and exudate C inputs are significant, but that increase will be moderated by an overall faster C mineralization rate of belowground C. N addition may slow soil C losses; however, the effect was minor and transient in this system. The labeled root-derived ¹³C was initially recovered in gram negative (highest enrichment), gram positive, and fungal biomarkers. With successive growing seasons, the labeled C in the gram negative and fungal markers declined, while gram positive markers continued to accumulate labeled belowground C. The rhizosphere of A. barbata shifted the microbial community composition, resulting in greater abundances of gram negative markers and lower abundances of gram positive, actinobacteria and cyclopropyl PLFA markers compared to unplanted soil. However, the longer-term utilization of labeled belowground C by gram positive bacteria was enhanced in the rhizosphere microbial community compared with unplanted soils. We suggest that the activities of gram positive bacteria may be major controllers of multi-year rhizosphere-related priming of SOM decomposition.     

种植制度对阴山北麓马铃薯种植区土壤温度的影响

通过马铃薯带状间作长期定位试验,测定了生育期内马铃薯与草谷子间作轮作(P-M)、间作连作(P+M),马铃薯与油菜间作轮作(P-R)、间作连作(P+R)地块10cm地温,并对相关结果进行分析.结果表明,各处理地温日变化呈明显的正弦曲线变化规律,轮作在6:30-9:00达最低温,16:30-18:00达最高温.相同生育期内轮作与连作比较,其平均最高、最低地温出现早0.5 ～1.5h,日较差大0.6 ～3.5℃.种植制度对日平均地温和积温的影响在不同生育期存在显著差异:苗期和块茎形成期,受不同前茬影响,轮作的平均地温和积温高于连作,与不同作物间作的处理间差异很小;块茎增长期和淀粉积累期,P-R的地温最低,P-M的最高.马铃薯块茎产量与全生育期日较差、生育前期的平均地温和日最高温、生育后期的日最低地温呈显著正相关.可见,提高苗期地温、增大各期日较差是轮作马铃薯高产的重要原因;与株高冠幅较大的油菜间作可以减少高温伤害,但在冷凉地区,与草谷子等低矮作物间作更容易获得充足的热量,从而实现高产.     

有益微生物组合加菌糠对小白菜生长及土壤养分的影响

采用盆栽试验 ,通过测定小白菜的株高、叶片长、叶比重、叶面积和产量 ,土壤碱解氮、有效磷、速效钾含量 ,研究不同有益微生物组合加菌糠对小白菜生长和土壤养分的影响。结果表明 :施用有益微生物组合加菌糠可以促进小白菜生长、增加其产量和提高土壤养分含量。其中 ,以有益微生物组合链霉菌和巨大芽孢杆菌加菌糠的效果最好。     

免耕与土壤侵蚀研究进展

综述了国内外免耕控制土壤侵蚀的机理研究以及对土壤性质的影响,并提出免耕在我国的应用方向。     

有机改良剂对温室土壤及番茄质量的影响

研究了优培-海藻生物有机肥(Y)、微生物菌肥(W)和腐植酸有机肥对日光温室土壤的理化性质、有效态微量元素含量、酶活性以及番茄品质等方面的影响,旨在探索快速、简易且廉价的土壤改良方法,为日光温室土壤改良及有机蔬菜生产提供理论依据。结果表明,不同土壤改良剂对土壤p H无显著影响,在番茄生育期内土壤p H值始终在7.0以上,没有出现酸化问题;拉秧后,除中量腐植酸有机肥(FM)外,其他各处理均能有效降低土壤EC值并达到极显著水平;各处理对提升有效态Mn、Zn和Fe含量的效果不显著,其中,仅高量腐植酸有机肥处理(FH)能同时提高开花结果盛期0~20 cm和20~40 cm土层的有效态Zn含量,与CK相比,分别增加10.8%和13.2%;不同土壤改良剂均可提高土壤脲酶和蔗糖酶活性;不同土壤改良剂对碱性磷酸酶的酶活性影响较小;微生物菌肥对酸性磷酸酶和过氧化氢酶的酶活性影响相对明显;不同土壤改良剂均能提高番茄可溶性固形物、可溶性糖、可滴定酸和维生素C的含量,其中,中量腐植酸有机肥处理提高了番茄的糖酸比。土壤改良剂可有效改善日光温室土壤特性及番茄品质。     

畜禽粪肥对土壤有效铜锌铁锰含量的影响

采用室内培养和DTPA浸提法研究了鸡粪、牛粪和猪粪等有机肥料对土壤有效Cu、Zn、Fe、Mn含量的影响。结果表明,在供试条件下施用鸡粪、牛粪和猪粪均可使土壤中有效Cu、Mn含量增加,但有效Zn含量降低;施用鸡粪可使土壤有效Fe含量增加,而施用牛粪和猪粪使土壤有效Fe含量降低。增加鸡粪施用量,可使土壤中有效Cu、Zn、Fe、Mn含量增加;培养期间有效Cu、Zn含量变化幅度较小,有效Fe、Mn含量变化较大。     

采煤塌陷裂缝对降雨后坡面土壤水分的影响

为探究采煤塌陷裂缝对坡面储蓄降水的影响,本文对降雨后不同坡向上裂缝两侧的不同土层水分动态变化特征进行了研究。结果表明:降雨主要补充坡面地表0~20 cm土层土壤水分,且在雨后0~20 cm土层土壤水分散失也较为严重;雨后阴坡土壤含水率最高,0~10cm、10~20cm和20~40 cm土层土壤水分差异显著(p0.05)。降雨结束8 d后,裂缝附近的土壤水分变化幅度较大,尤以坡面裂缝上部边缘处最为明显,裂缝处与远离裂缝的土壤水分之间差异显著(p0.05);阳坡土壤水分损失最高,阳坡裂缝周边土壤水分平均损失量高达3.31%。可见,裂缝的出现会在一定程度上打破坡面储蓄降水的格局,加剧坡面局部土壤水分散失,这一点在植被恢复与建设过程中不容忽视。     

猪粪施用量对红壤旱地理化性质及酶活性的影响

为研究猪粪的合理施用及其对红壤旱地地力提升的效应,利用在第四纪红壤旱地中连续3年分别施用0、7.5、15、30、45 t·hm^-2猪粪的小区定位试验,比较不同处理下菠菜和玉米地上部生物量、土壤相关理化性质、碳氮磷循环相关酶活性的差异。结果表明:菠菜和玉米地上部生物量、土壤有机质、土壤全量和速效态氮磷钾含量均随猪粪施用量的增加呈线性增加。当猪粪施用量达45 t·hm^-2时菠菜、玉米平均地上部生物量分别达到11.48、20.84 t·hm^-2,土壤有机质和全氮、全磷含量分别达14.6、1.07、0.73 g·kg^-1,土壤碱解氮、有效磷、速效钾含量分别达85.47、106.9、411.7 mg·kg^-1,但与猪粪施用量为15和30t·hm^-2时土壤养分含量的差异不显著,而土壤中与碳氮磷循环相关的6种酶活性则与猪粪施用量呈线性相关,且在施用量为30或45t·hm^-2时出现显著差异;6种酶活性与土壤有机质、养分含量间均具有显著或极显著正相关关...     

Wind erosion and airborne dust deposition in farmland during spring in the Horqin Sandy Land of eastern Inner Mongolia, China

In the Horqin Sandy Land of eastern Inner Mongolia in northern China, wind erosion in farmland is very common in a period from thawing of frozen surface soil in mid-March to sowing of crops in the end of April, largely because of dry and windy weather. However, little is known about the magnitude of wind erosion and associated nutrient losses due to erosion and the addition of nutrients by airborne dust deposition to farmlands during this period. A field experiment was conducted in an Entisol with sand origin under corn (Zea mays L.) production to investigate daily changes in wind speed and wind erosion intensity (as measured by soil transport rate) over a period from 20 March to 30 April 2001. We also measured daily rates of airborne dust deposition during the spring seasons with the high frequency of dust storm occurrence. The rates of soil transport by wind varied greatly from 13.2 to 1254.1 kg ha⁻¹ per day, averaging 232.1 kg ha⁻¹ per day, largely attributable to great variation between days in wind speed within the study period. The potential losses of nutrients through wind erosion were 0.26–24.95 kg ha⁻¹ per day (averaging 4.62 kg ha⁻¹ per day) in organic matter, 0.02–1.64 kg ha⁻¹ per day (averaging 0.31 kg ha⁻¹ per day) in nitrogen and 0.01–0.7 kg ha⁻¹ per day (averaging 0.13 kg ha⁻¹ per day) in phosphorus. The mean rates of airborne dust deposition ranged from 4.0 to 48.9 kg ha⁻¹ per day, averaging 19.9 kg ha⁻¹ per day, during the spring seasons. The potential addition of organic matter, nitrogen and phosphorus by dust input to the experimental field was, on average, 0.54, 0.04 and 0.02 kg ha⁻¹ per day, respectively. Although the addition was a fraction of the losses due to erosion, nevertheless, dust input in the spring seasons is one of the major suppliers of soil nutrition. The fact that the addition of nutrients by dust is about 1/10 of the losses of soil nutrients through wind erosion suggests that developing and adopting more effective management practices to reduce soil erosion losses and to improve soil fertility are crucial to achieve a sustainable agricultural system in a fragile, semiarid sandy land environment.