Changes in Vertisol properties as affected by organic amendments application rates

There is considerable global interest in using recycled organic materials because of perceived benefits to soil health and environment. However, information on the effects of organic waste products and their optimal application rates on the quality of heavy clay soils such as Vertisols is sparse. An incubation experiment was therefore conducted using five organic amendments at various rates to identify their optimal application rates, which could improve the quality of the Vertisol. Cotton gin trash, cattle manure, biosolids (dry weight basis 7.5–120 t/ha), chicken manure (dry weight basis 2.25–36 t/ha) and a liquefied vermicast (60–960 L/ha, volumetric basis) changed the soil chemical, physical and microbiological properties compared with a control where no amendments were applied, viz. higher light fraction of organic matter, nutrient content (N and P) and soil microbial activity. Higher application of chicken manure resulted in an increase in dry‐sieved mean weight diameter. Increasing rates of cattle manure increased exchangeable Na concentration and ESP. Although vermicast itself did not contribute a significant amount of N into the soil, when applied at higher rates (60–960 L/ha), its application resulted in increased concentration of NO₃‐N in soil by amounts ranging from 43 to 429%. Optimal application rates for cattle manure and cotton gin trash were 30 t/ha, whereas for biosolids and chicken manure, the optimum rate was 60–18 t/ha, respectively.     

Transport of zinc,copper, and lead in a sewage sludge amended calcareous soil

The application of sewage sludge on farmland is practised in many countries since sludge is rich in macro- and micro- nutrients. However, increasing use of sewage sludge on farmland has raised concerns about the potential transport of heavy metals into food chains and groundwater. This study determined for a calcareous soil the effects of sludge application on soil physical properties and transport of zinc (Zn), copper (Cu), and lead (Pb). Secondary anaerobic digested sewage sludge was applied at rates of 0, 25, 50, and 100 t/ha (on a dried weight basis) for four consecutive years and mixed in the top 20-cm of soil. Corn (Zea mays L.) was planted as a spring crop, followed by wheat (Triticum aestivum) as a winter crop. Sludge application increased the dissolved organic matter content and modified the soil structure, increased the soil infiltration rate, saturated hydraulic conductivity, and aggregate stability, and decreased the bulk density. Sludge application greatly increased DTPA (diethylenetriamine pentaacetic acid)-extractable soil metal concentrations to 50 cm depth and significantly to 1 m. In the plots that received four application of 100 t/ha sewage sludge, the mean concentrations of Zn, Cu, and Pb in subsoil increased by 1600, 7, and 4.5 times, respectively, compared with the control. The results indicate that a combination of enhanced soil physical properties, heavy and inefficient irrigation and high organic matter content with heavy metals cause significant metal mobility. High sludge applications pose risks of groundwater and food chain contamination and rates are best restricted to those reflecting the nutrient demand of crops (20 t/ha every 4 to 5 yr or an average of 4 to 5 t/ha/yr).     

新型土壤改良剂Arkadolith对沙质土壤主要物理性质的影响

通过室内盆栽试验,研究了新型土壤改良剂Arkadolith不同施用率（0,4%,8%,12%,16%）对风沙土主要物理性质的影响。结果表明:施加土壤改良剂Arkadolith降低了土壤容重和比重,提高了土壤孔隙度与孔隙比;能明显降低沙质土壤中砂粒的含量,粒级0.05～0.01 mm的粉粒比对照降低12.5%～18.3%,提高了黏粒和物理性黏粒的含量,使原来无黏粒的沙土出现了少量的黏粒,<0.01 mm物理性黏粒增加3.3～4.0倍。施加土壤改良剂Arkadolith改良了土壤结构,4种处理土壤各粒级团聚体相较于对照均有明显的增加,以>5 mm和>0.25 mm两者为例,增加幅度分别为28.84%～66.67%和28.21%～63.49%。同时土壤改良剂Arkadolith的施用改善了沙土的持水能力和供水水平,且持水能力表现为随着改良剂施用率增加而增强。这些指标表明,施用土壤改良剂Arkadolith能有效地改善沙质土壤物理特性,增强沙土的保水能力。     

Influence of compost amendments on the hydraulic functioning of brownfield soils

This study assessed the impact of compost on the hydraulic properties of three soils (sandy loam, clay loam and diesel‐contaminated sandy loam) with relatively poor physical quality typical of brownfield sites. Soils were amended with two composts at 750 t/ha. Samples were also collected from a clay‐capped brownfield site, previously amended with 250, 500 or 750 t/ha of compost. Water‐release characteristics and saturated hydraulic conductivity were determined for all soils and physical quality indicators derived. Unsaturated flow in field profiles after compost application with two depths of incorporation and two indigenous subsoils was simulated using Hydrus‐1D. Compost generally increased water retention. Hydraulic conductivity tended to decrease following compost application in sandy loam but increased in clay and clay loam, where compost addition resulted in a larger dominant pore size. Although compost improved physical quality indicators, they remained suboptimum in clay and clay loam soil, which exhibited poor aeration, and in the contaminated sandy loam, where available water capacity was limited, possibly due to changes in wettability. Increasing application rates in the field enhanced water retention at low potentials and hydraulic conductivity near saturation but did not alter physical quality indicators. Numerical simulation indicated that the 500 t/ha application resulted in the best soil moisture regime. Increasing the depth of incorporation in the clay cap improved drainage and reduced waterlogging, but incorporation in more permeable subsoil resulted in prolonged dry conditions to greater depths.     

渭北旱塬管理措施对冬小麦地土壤剖面物理性状的影响

【目的】研究黄土高原旱作农业区不同施肥覆盖措施对冬小麦地0—40 cm土壤剖面物理性质的影响,可为保持良好的土壤物理性状,探求适合渭北旱塬可持续的田间管理措施提供参考。【方法】基于设在渭北旱塬15年的田间定位试验,选取NP (N 150 kg/hm^2+P 75 kg/hm^2)、NPK (NP+K 30 kg/hm^2)、NPB (NP+biochar 14.0t/hm^2)、NPFFT (NP配合地膜夏闲期覆盖)、NPFGT (NP配合地膜生育期覆盖)和NPFWT (NP配合地膜全年覆盖)共6个处理。于2017年冬小麦收获期采集剖面土样,对0—10 cm、10—20 cm、20—30 cm和30—40 cm土层土壤含水量、土壤容重、饱和导水率和水稳定性团聚体等相关土壤物理性质进行测定与分析。【结果】与NP相比,NPK处理降低了收获期0—20 cm土壤容重,增加了耕层土壤总孔隙度和0—40 cm土层> 2 mm水稳定性团聚体含量,0—10 cm土层> 2 mm水稳定性团聚体含量显著提高了1.3倍(P <0.05);NPB处理,收获期耕层土壤容重降低,土壤总孔隙度增加,表层土壤饱和导水率显著降低27.9%,剖面土壤含水量和> 2 mm水稳定性团聚体含量均增加,且表层> 2 mm水稳定性团聚体含量显著提高了1.0倍;NPFFT处理收获期剖面土壤含水量降低,耕层土壤容重增加,总孔隙度降低;NPFGT处理收获期耕层土壤容重和剖面土壤含水量均增加,耕层总孔隙度降低,剖面土壤饱和导水率降低,尤其表层显著降低60.2%;NPFWT处理收获期耕层土壤容重增加,总孔隙度降低,表层土壤饱和导水率降低,但10—40 cm土壤饱和导水率平均提高57.5%,剖面土壤含水量、> 2 mm水稳定性团聚体含量、平均重量直径和几何平均直径均增加。受当地传统耕作深度的影响,不同施肥覆盖措施对土壤容重、饱和导水率和孔隙度的影响主要集中在0—20 cm土层,对20—40 cm土层影响较小。【结论】在氮磷肥配施的基础上,增施钾肥、生物炭和地膜全年覆盖均有利于改善试验农田土壤物理性质,但从经济投入和对土壤物理性状改良程度方面考虑,增施钾肥和地膜全年覆盖这两种处理是保持渭北旱塬良好土壤剖面物理性质的有效措施。     

麦茬复种饲料油菜对耕层土壤团聚体的影响

通过田间小区试验，研究了不同油菜种植密度与施氮肥对麦茬复种饲料油菜耕层（0～20cm）土壤颗粒组成、水稳性团聚体、微团聚体、粘粒分散率和团聚度的影响。试验结果表明，麦茬复种油菜能提高耕层土壤水稳性团聚体，改善土壤颗粒组成状况；与对照（CK）相比，耕层土壤粘粒分散率呈显著或极显著性降低，〈0．001mm的土壤团聚体破坏率和特征微团聚体比例（〈0．01mm／〉0．01mm）显著降低，而土壤团聚度在油菜苗期为降低趋势，收获期呈显著或极显著性增加，〉0．25mm的土壤团聚体百分含量除收获期的水稳性团聚体外均呈不显著性降低。复种油菜对土壤水稳性团聚体改善贡献高于土壤微团聚体。种植密度和施肥处理均能不同程度地影响和改变耕层土壤水稳性团聚体、微团聚体和粘粒分散率的含量，处理间规律性不强，差异性并不十分显著。说明麦茬复种饲料油菜对农田土壤肥力的改善和提高具有积极作用。     

不同秸秆施用方式下接种蚯蚓对土壤团聚体及其中碳分布的影响

通过室内培养试验,研究在施用有机物条件下接种蚯蚓对土壤团聚体的分布、团聚体的水稳性以及不同粒径的水稳性团聚体中有机碳含量的影响.干筛结果表明,不同秸秆施用方式下,蚯蚓接种能显著促进各个处理中＞2 mm团聚体含量的增加,且在秸秆混施的处理中表现得尤为明显,团聚体含量增加了2.95倍;湿筛结果表明,蚯蚓在不施和混施秸秆的处理中能显著降低土壤黏砂粒含量,即增加土壤中水稳性团聚体的含量,但是在表施秸秆的处理中显著降低了0.25～ 0.053 mm粒级团聚体含量,使之分散为黏砂粒.蚯蚓和秸秆对土壤团聚体分布和水稳性的影响都达到显著水平.蚯蚓对水稳性微团聚体的影响极显著,而秸秆的作用更多地表现在水稳性大团聚体上.在秸秆表施和秸秆混施条件下,接种蚯蚓均显著促进了微团聚体碳含量的增加,分别为相应对照的2.1和1.2倍.蚯蚓作用能显著降低黏砂粒有机碳在全碳中含量,增加团聚体有机碳含量,主要是由于蚯蚓的作用能促进黏砂粒黏结为团聚体.     

Soil erosion and changes in the physical properties of Lithuanian Eutric Albeluvisols under different land use systems

Abstract

The investigations aimed to: 1) evaluate water erosion rates on undulating slopes in Lithuania under different land use systems; 2) study changes in soil physical properties on the differently eroded slopes; and 3) better understand relationships between soil physical properties and soil erodibility. Research data were obtained on loamy sand and clay loam Eutric Albeluvisols located on the undulating hilly relief of the ?emai?iai Uplands of Western Lithuania. The results of 18 years of water erosion investigations under different land use systems on slopes of varying steepness are presented. Attention is focused on changes in soil physical properties in relation to soil erosion severity. Measured water erosion rates in the field experiments were: 3.2–8.6 m³ ha^?1 yr^?1 under winter rye, 9.0–27.1 m³ ha^?1 yr^?1 under spring barley and 24.2–87.1 m³ ha^?1 yr^?1 under potatoes. Perennial grasses completely prevented water erosion, while erosion-preventive grass-grain crop rotations (67% grasses, 33% cereal grains) decreased soil losses by 75–80% compared to the field crop rotation, containing 17% tillage crops (potatoes), 33% grasses and 50% cereal grains. The grain-grass crop rotation (33% grasses and 67% cereal grains) decreased soil erosion rates by 23–24%. The percentage of clay-silt and clay fractions of arable soil horizons increased, while the total soil porosity and moisture retention capacity decreased with increased soil erosion. Phytocenoses, including sod-forming perennial grasses and grass-grain crop rotations, led to changes in the physical properties of eroded soils; soil bulk density decreased and percentage total porosity and moisture retention capacity increased. The grass-grain crop rotations increased the water-stable soil structure (measured as water-stable soil aggregates) by 11.03 per cent units and sod-forming perennial grasses increased aggregate stability by 9.86 per cent units compared with the grain-grass crop rotation on the 10–14° slope. Therefore, grass-grain crop rotations and sod-forming perennial grasses decreased soil erodibility and thus could assist both erosion control and the ecological stability of the vulnerable hilly-undulating landscape.     

黄土塬区旱作农田长期定位施肥对冬小麦水分利用的影响

对长期定位施肥试验第22年度的测定数据进行了分析,探讨了旱地施肥对冬小麦水分利用的影响。试验结果表明,测定年份冬小麦的耗水深度受播种前雨季降雨入渗深度的影响位于地下200 cm左右。长期施肥单施磷肥处理,播种期土壤有效贮水量与不施肥的对照接近,而单施氮肥,氮磷配施和氮磷钾配施均显著低于对照;在施P2O5 90 kg/hm2配施氮肥或施N 90 kg/hm2配施磷肥,随着施氮量或施磷量从0增加到180 kg/hm2,播种期土壤有效贮水量均逐渐降低,但前者作物的土壤水分消耗表现出降低趋势,而后者表现出增加趋势。与对照相比,各施肥处理均提高了土壤有效底墒的利用率。氮磷配施比单施磷肥降低了土壤供水占作物耗水的比例,使得作物生长和产量的形成对当季降水的依赖性增加。与对照相比,氮磷配施及氮磷钾配施显著提高了冬小麦收获指数、产量和水分利用效率,而单施磷肥和氮肥使收获指数、产量和水分利用效率显著降低。施P2O5 90 kg/hm2的条件下,不同施氮量之间收获指数差异较小,而产量和水分利用效率均高于单施磷肥;施N 90 kg/hm2的条件下,不同施磷量作物的收获指数、产量和水分利用效率均得到提高。     

Remediation of Cadmium Pollution in Soils by Different Amendments: A Column Study

Abstract

A column study was conducted to determine the effect of city compost, lime, gypsum, and phosphate on cadmium (Cd) mobility in three well‐recognized benchmark soils of India [viz., (Islamnagar) Vertisol, (Amarpur) Inceptisol, and (Khala) Alfisol]. Columns made of PVC were filled with soil treated with different treatment doses [viz., 0.5% city compost, 1% city compost, 2% city compost, 2.5 t lime/ha, 5 t lime/ha, 2.5 t lime/ha+0.5% city compost, 2.5 t gypsum/ha, 2.5 t gypsum/ha+0.5% city compost, and 100 kg P₂O₅/ha as potassium phosphate (KH₂PO₄). The columns were leached with 100 mg L^?1 Cd under saturated condition. The amount of water moving through the soils was measured as the pore volume. A delayed breakthrough curve (BTC) of Cd in the presence of lime has been observed in all the studied benchmark soil series. Among the treatments, lime application reduced the movement of Cd from surface soil to lower depth of soil to a large extent resulted in 9, 25, and 45% more retention of Cd in surface soil of the Islamnagar, Amarpur, and Khala series respectively. Explanation for reduced Cd mobility in limed soil can be derived from pH changes of soils. In comparison to control soil, phosphate application caused 6, 21, and 30% more retention of Cd in surface soil in the Islamnagar, Amarpur, and Khala series, respectively. Combined application of lime and city compost reduced the movement of Cd in the soil profile. It appears that organic matter controls the sorption of Cd in soils. The amount of Cd sorbed increased with increasing organic carbon content, but gypsum application may leach Cd beyond the root‐zone depth. A rapid breakthrough curve was observed under gypsum‐treated soils. Retardation factor revealed that a somewhat lower degree of Cd retention occurred in the Khala series, which might possibly be attributed to less clay content and low pH. Overall, the column study indicated that total Cd accumulation occurred up to depths of 5–7.5 cm, 7.5–10 cm, and 10–15 cm in soils of Islamnagar, Amarpur, and Khala series, respectively.     

长期施肥下红壤有机碳及其颗粒组分对不同施肥模式的响应

采集不同施肥24年的红壤,采用物理分组的方法,观测了长期不同施肥下红壤有机碳及其组分变化,并结合历史资料分析了不同施肥模式对红壤有机碳及其颗粒组分的影响。结果表明,化肥配施有机肥（NPKM）处理下红壤总有机碳含量（10.33 g/kg）,砂粒（2000～53 m）、细粉粒（5～2 m）和粘粒（2 m）组分中的有机碳含量显著高于其他处理。与不施肥（CK）相比,施用化肥（NPK、2NPK）和有机肥（NPKM、M）显著地提高了红壤有机碳在砂粒和粘粒中的分配比例,而降低了其在粗粉粒和细粉粒的分配比例。施化肥（NPK、2NPK）、单施有机肥（M）、化肥配施有机肥（NPKM）处理,土壤有机碳的平均固定速率分别为0.05 t/(hm2?a)、0.18 t/(hm2?a)、0.26 t/(hm2?a)。相关分析表明,不同施肥模式下红壤有机碳的固定量与碳投入量之间存在着极显著的线性相关关系（R2=0.909, P0.01）,土壤的固碳效率为8.1%;随着碳投入的增加,粗粉粒和细粉粒有机碳储量逐渐下降,而砂粒和粘粒中碳储量逐渐增加,并且粘粒增加速率要远远高于砂粒。以上结果说明,红壤中有机碳还没有达到饱和,还具有一定的固碳潜力,增加的有机碳主要固持在粘粒中,粘粒是红壤有机碳的主要固持组分。     

Soil properties influencing erodibility of soils in the Ntabelanga area,Eastern Cape Province,South Africa

Soil erosion has serious off-site impacts caused by increased mobilization of sediment and delivery to water bodies causing siltation and pollution. To evaluate factors influencing soil erodibility at a proposed dam site, 21 soil samples collected were characterized. The soils were analyzed for soil organic carbon (SOC), exchangeable bases, exchangeable acidity, pH, electrical conductivities, mean weight diameter and soil particles’ size distribution. Cation exchange capacity, exchangeable sodium percentage, sodium adsorption ratio, dispersion ratio (DR), clay flocculation index (CFI), clay dispersion ratio (CDR) and Ca:Mg ratio were then calculated. Soil erodibility (K-factor) estimates were determined using SOC content and surface soil properties. Soil loss rates by splashing were determined under rainfall simulations at 360?mmh^?1 rainfall intensity. Soil loss was correlated to the measured chemical and physical soil properties. There were variations in soil form properties and erodibility indices showing influence on soil loss. The average soil erodibility and SOC values were 0.0734?t?MJ^?1?mm^?1 and 0.81%, respectively. SOC decreased with depth and soil loss increased with a decrease in SOC content. SOC significantly influenced soil loss, CDR, CFI and DR (P??1. Addition of organic matter stabilize the soils against erosion.     

石灰岩区土壤分形特征及其与土壤性质的关系

研究了岩溶坡地不同生态系统土壤颗粒组成和团粒结构的分形特征.结果表明,土壤颗粒组成分形维数与黏粒及物理性黏粒含量显著正相关,与砂砾含量显著负相关.团粒结构分形维数与水稳性团聚体含量显著负相关,与团聚体湿筛后的破坏率显著正相关,即分形维数愈高,>0.25 mm水稳性团聚体和水稳性大团聚体含量愈低;团粒结构的分形维数与土壤有机质有负相关趋势,与土壤阳离子交换量显著负相关,与土壤体积质量(容重)呈正相关趋势.次生灌丛岩溶生态系统退化后,土壤黏粒减少,体积质量上升,土壤水稳性团聚体含量及其稳定性下降,土壤颗粒组成分形维数降低,土壤团粒结构分形维数则呈上升趋势.颗粒组成分形维数与团粒结构分形维数对土壤质量和岩溶生态环境状况的反映是一致的.     

Microbial activity and metabolic quotient of microbes in soils amended with biochar and contaminated with atrazine and paraquat

The study was conducted to determine how biochar as a soil amendment maintained the microbial community in pesticide contaminated soils. Alfisol (Adenta series – Typic Kandiustalf) and Vertisol (Akuse series – Typic Calciustert) were amended with biochar (0 t/ha biochar, 10 t/ha cocoa husk biochar (CHB), 10 t/ha rice husk biochar (RHB)) and pesticides (atrazine and paraquat at two rates each namely 0 kg/ha pesticide and 10 times the normal recommended rate of pesticide) were applied. The CHB-amended soils stimulated microbial activities such as ammonia and nitrate release more than the RHB-amended soils. Basal respiration was significantly higher in the atrazine polluted soils than in paraquat polluted soil. Significant interaction occurred between soil type and biochar and high microbial biomass carbon was recorded for vertisol amended with CHB. Metabolic quotient was lower in soils amended with biochar and polluted with atrazine than in the un-amended soil. The use of CHB in soil of high clay content (47.5%, i.e. the vertisol) was a more effective management tool in maintaining the microbial community in a pesticide-polluted environment than in soil of lower clay content (22.5%). Soils of high clay content amended with biochar can sustain the soil microbial community even in a disturbed environment.     

Effects of biochar and phosphorus fertilizer rates on soil physical properties and wheat yield on clay textured soil in middle Nile Delta of Egypt

ABSTRACT

Biochar has not been adequately used by farmers to improve the clay textured soil productivities in the world. Therefore, the objective of this study is to investigate the effect of the co-application of biochar with different rates of phosphorus (P) fertilizer on selected soil physical properties and wheat yield on clay textured soil over two growth seasons. Biochar treatments occupied the main plots at a rate of 0.0 and 10 t ha^?1, while the sub-plots were devoted to phosphorus rates at rates of 0%, 50%, 100%, and 150% of recommended P fertilizers. Biochar (10 t ha^?1) and P at different rates decreased soil bulk density significantly. Meanwhile, it increased aggregate stability, saturated hydraulic conductivity and soil water retention significantly at (p < .05), and it improved the grain yield of wheat. More grain yields in the soil treated with biochar than untreated soil under all P application rates for both years were probably caused partially by more nutrients (N, P, and K) were applied from biochar itself. Grain yield of wheat in the soil-amended biochar and P did not increase significantly between the application at 50%, 100% and 150% P. The results of this study indicate that phosphorus blends with biochar can be used to decrease the bulk density of clay textured soils and to improve crop production in these soils.     

膨润土和有机肥施用对秸秆覆盖还田紫色土肥力影响及经济效益分析

  目的  明确施用膨润土和有机肥对紫色土秸秆还田下土壤肥力及经济效益的影响,探讨提高紫色土区秸秆还田转化效率的技术方法,实现秸秆资源的高效利用。  方法  应用田间小区试验方法并结合多元统计分析,比较玉米－油菜轮作模式下,紫色土秸秆覆盖还田时施用膨润土和有机肥对土壤肥力、作物产量及年均收益等方面的差异。  结果  施用膨润土和有机肥可分别使土壤容重降低12.31%和18.78%,土壤全量和速效氮、磷、钾含量分别增加27.42% ~ 71.39%和14.98% ~ 86.11%。同时,施用膨润土和施用有机肥对增加土壤有机碳及作物产量也具有较好的促进作用。在考虑产出－投入成本的情况下进行经济效益分析,发现施用膨润土和有机肥后玉米-油菜的年均产量当量分别提高了28.15%和28.73%,年均产值分别增加了0.31和0.81万元hm?2。通过灰色关联分析、主成分分析及聚类分析,发现土壤含水量和环境日均温差是施用膨润土和有机肥提升秸秆覆盖还田紫色土中作物产量的关键调控因子。  结论  在秸秆覆盖还田紫色土区,通过施用膨润土和有机肥可有效提高土壤有机质及养分库容,改善土壤结构,促进作物增产增收,其中以施用膨润土效果更佳。     

Dynamics of the agrochemical fertility parameters of arable soils in the southwestern region of Central Chernozemic zone of Russia

Data of the agrochemical survey of arable soils in Belgorod oblast during the period from 1964 to 2014 have been analyzed. The soil cover mainly consists of typical chernozems (Haplic Chernozems) and leached chernozems (Luvic Chernozems) in the forest-steppe zone and ordinary chernozems (Calcic Chernozems) in the steppe zone. Under long-term agricultural use (from 1964 to 2014), the content of mobile phosphorus in arable soils of the region under study has increased from 55 to 137 mg/kg, and the content of mobile potassium has increased from 105 to 147 mg/kg. During the period of 1976–2014, the share of acid soils has increased from 22.8 to 45.8%, including medium-acid soils from 1.5 to 12.6%. No significant changes in the weighted average content of soil organic matter are revealed for the period from 1985 to 2014. The value of this parameter is within the range of 4.8–5.0%. In the 2010–2014, 95.0% of arable soils belonged to the category of low supplied with mobile sulfur; 99.2, 96.9, 94.1, and 54.4% of soils were poorly supplied with zinc, copper, cobalt, and manganese, respectively. During the same period, the maximum average productivity of the crop area (3710 f. u./ha) was noted at the application of 4.8 t/ha organic fertilizers and 97.9 kg/ha organic fertilizers on the average. The maximum long-term yields of sugar beet (36.8 t/ha) and corn grain (4.97 t/ha) were obtained at the application of relatively low fertilizer rates.     

人工栽培中麻黄对荒漠化土壤理化性质的影响

在河西走廊荒漠化土壤上种植中麻黄,改土培肥效果十分明显。3年生麻黄草鲜草重12.17t/hm2,折干重4.87t/hm2,与CK比较0~20cm土层中自然含水量增加64.29g/kg,>0.25mm团粒结构增加14.31%,总孔隙度增加11.32%,体积质量(容重)降低0.30g/cm3,pH由8.32降到7.99,全盐含量降低1.72g/kg,脱盐率达到49.85%,有机质、速效N、P、K亦随之增加。     

不同稻秆炭和竹炭施用水平对小青菜产量、品质以及土壤理化性质的影响

为探明不同添加水平的两种生物炭对小青菜产量、 品质及土壤理化性质的影响，为生物炭在蔬菜生产中的有效利用提供依据，开展田间种植试验，在配施氮肥情况下分别添加0、 5、 10、 20、 40 t/hm2 稻秆炭和竹炭，结果表明，高水平施加稻秆炭和竹炭（20 t/hm2、 40 t/hm2）均能显著降低菜地土壤容重，提高土壤pH、 有机碳、 全氮和速效钾含量，但对土壤有效磷和阳离子交换量未产生显著性影响；两种生物炭对小青菜增产均具有促进作用；当添加量为 40 t/hm2 时，稻秆炭和竹炭使小青菜维生素C 含量有所升高，总糖含量分别升高31.2% 和19.5%，硝酸盐含量分别降低15.0% 和16.4%，综合效果稻秆炭优于竹炭，而对小青菜粗纤维和蛋白质的作用不明显。施加生物炭有利于增加土壤孔隙度，提升土壤肥力，改善小青菜品质。生物炭可作为土壤改良剂施用于蔬菜，但具体施用量需根据生物炭和蔬菜种类来确定。     

Accumulation and movement of phosphorus from poultry litter application on a Starr clay loam

Abstract

The poultry industry faces tremendous challenges for the economically sound and environmentally safe disposal of the massive amounts of waste it generates during production processes. This study was conducted to investigate the accumulation and downward movement of phosphorus (P) from surface application of poultry litter (PL) on a Starr clay loam (fine‐loamy, mixed, thermic Fluventic Dystrochrepts). Poultry litter was surface applied to unimproved pasture at rates of 5.8, 11.4, 17.2, 22.9, and 28.7 mt/ha in 1991 and 4.1, 8.0, 12.1, 16.1, and 20.2 mt/ha in 1992, respectively. Cumulative P levels supplied by the PL over the two‐year period were 105.8, 211.7, 317.5, 423.3, and 529.1 kg/ha. Phosphorus from both PL and inorganic sources accumulated in the zone of application. The Mehlich 3 (M3)‐extractable P levels varied with rate of P application for each of the two years of this study. In 1992, M3‐extractable P levels were increased by 2‐, 4‐, 6‐, and 8‐fold over the control by PL application in the 0 to 5 cm depth. In 1993, the highest rate of PL application (20.2 mt/ha) increased M3‐extractable P levels by almost 18‐fold over the control (192 mg P/kg versus 11 mg P/kg). In 1992, downward movement of P occurred into the 5.0 to 10.0 and 10.0 to 15.0 cm layers from the highest rate of PL application (28.7 mt/ha). By 1993, P moved into the 5.0 to 10.0 and 10.0 to 15.0 cm soil layers from the second highest PL application rate as well. This downward movement of surface‐applied P in the Starr soil with a high fixation capacity was attributed to mobility of organic‐bound P.