黔东南州天柱县植烟土壤保育与改良研究

植烟土壤是确保烤烟优质高产的关键因素之一,通过对天柱县植烟土壤烟田基本情况、土壤退化情况、土壤保育与改良情况、土地整理情况等进行调查,结果表明:该烟区地块比较破碎,有便利的排水条件或健全的排水设施,无洪涝灾害的烟田面积为420.00 hm~2,占63.0%;土壤板结发生面积为136.00 hm~2,占基本烟田的20.4%;有机质含量下降发生面积为208 hm~2,占基本烟田的31.2%;水土流失发生面积为169.33 hm~2,占基本烟田的25.4%。为此,应采取土壤改良措施,以促进天柱特色优质烤烟的发展。     

Efficiency of wheat straw mulching in reducing soil and water losses from three typical soils of the Loess Plateau,China

Mulching the soil surface with a layer of plant residue is considered an effective method of conserving water and soil because it increases water infiltration into the soil, reduces surface runoff and the soil erosion, and reduces flow velocity and the sediment carrying capacity of overland flow. However, application of plant residues increases operational costs and so optimal levels of mulch in order to prevent soil and/or water losses should be used according to the soil type and rainfall and slope conditions. In this study, the effect of wheat straw mulch rate on the total runoff and total soil losses from 60-mm simulated rainstorms was assessed for two intensive rainfalls (90 and 180 mm h⁻¹) on three slope gradients typical conditions on the Loess Plateau of China and elsewhere. For short slopes (1 m), the optimal mulch rate to save water for a silt loam and a loam soil was 0.4 kg m⁻². However, for a clay loam soil the mulch rate of 0.4 kg m⁻² would be optimal only under the 90 mm h⁻¹ rainfall; 0.8 kg m⁻² was required for the 180 mm h⁻¹. In order to save soil, a mulch rate of 0.2 kg m⁻² on the silt loam slopes prevented 60%–80% of the soil losses. For the loam soil, mulch at the rate of 0.4 kg m⁻² was essential in most cases in order to reduce soil losses substantially. For the clay loam, 0.4 kg m⁻² may be optimal under the 90 mm h⁻¹ rain, but 0.8 kg m⁻² may be required for the 180 mm h⁻¹ rainstorm. These optimal values would also need to be considered alongside other factors since the mulch may have value if used elsewhere. Hence doubling the optimal mulch rate for the silt loam soil from 0.2 kg m⁻² or the clay loam soil under 90 mm h⁻¹ rainfall from 0.4 kg m⁻² in order to achieve a further 10% reduction in soil loss needs to be assessed in that context. Therefore, Optimal mulch rate can be an effective approach to virtually reduce costs or to maximize the area that can be treated. Meantime, soil conservationist should be aware that levels of mulch for short slopes might not be suitable for long slopes.     

中国大蒜主产区主要品种鳞茎品质及其与产地土壤养分的关系

以全国16个省区50个品种大蒜与对应土壤为材料,分析大蒜鳞茎中大蒜素、硒元素、锗元素、可溶性糖、可溶性蛋白的含量,测定蒜瓣数、蒜头质量等7个鳞茎性状及土壤化学性状指标,通过主成分分析对鳞茎性状进行综合评价,分析大蒜鳞茎与产地土壤化学性质的相关性。结果表明:大蒜素、硒、锗和可溶性糖4个主成分累计方差贡献率达到79.8%,反映大蒜品种鳞茎品质的基本信息。鳞茎营养品质大蒜素、硒、锗、可溶性糖、可溶性蛋白及表型品质蒜瓣数、蒜头质量综合排序,品质较好的(F≥0.5)品种是‘苏02’‘苏01’‘贵02’‘豫07’和‘晋01’,品质一般(0≤F0.5)的品种19个,品质较差(F0)的品种超过一半。相关分析表明,土壤养分含量与大蒜品质间的相关性较小,只有硫元素与大蒜素和可溶性糖显著正相关,土壤pH与大蒜锗含量显著正相关,土壤N含量与大蒜可溶性糖极显著正相关。     

长期施用沼肥对设施菜田土壤养分和盐分累积量的影响

为研究规模养猪场沼液沼渣在农田施用对土壤养分及盐分含量累积的影响,以安康市某养猪场农业园区施用沼液设施菜田土壤为研究对象,以当地常规施用化肥设施菜田为对照,定点采集施用沼肥区和对照区0 a、1 a、3 a、5 a和7 a的设施菜地土壤,分别测定土壤中碱解氮、有效磷、速效钾、有机质、全铜、全锌质量分数及电导率和pH。结果表明,随着沼液沼渣施用年限的增加,土壤中碱解氮、有效磷、速效钾、有机质、全铜、全锌质量分数和电导率均相应增加,7 a后分别达96.1 mg/kg、91.5 mg/kg、73.7 mg/kg、11.9 g/kg、118.5 mg/kg、263.4 mg/kg和0.366 mS/cm,分别是未施用沼液沼渣土壤中各成分含量的3.4倍、1.5倍、3.3倍、1.3倍、3.9倍、1.88倍和4.74倍,说明施用沼液沼渣能有效增加土壤养分含量,同时土壤养分和盐分快速累积,对土壤环境带来较大的污染风险。     

生草对南疆温室桃园土壤理化性状的影响

研究生草措施对温室桃园土壤环境和养分的影响,为温室桃栽培优质生产提供理论支持。以温室桃园为研究对象,设置行间种植三叶草和小黑麦为处理,以清耕为对照,测定温室桃园土壤理化性质、体积质量、孔隙度及养分含量的变化。结果表明,温室桃园行间种植三叶草和小黑麦能减缓土壤温度变化幅度,提高土壤含水量,降低土壤水溶性总盐含量,显著增加0～20 cm土层和20～40 cm土层土壤有机质及养分含量,其中种植三叶草的效果好。生草能增加土壤pH,显著降低0～20 cm土壤体积质量,增加土壤总孔隙度。温室桃园生草可以有效调节土壤温度,改善土壤结构和通透性,提高土壤肥力。     

施磷量对柴达木枸杞产量与品质及土壤酶活性的影响

以树龄8 a的‘宁杞7号’为试验材料，通过施用不同量的磷肥（P₂O₅）［0 kg/hm(P₀)、133 kg/hm(P₁₃₃)、267 kg/hm(P₂₆₇)、400 kg/hm(P₄₀₀)、534 kg/hm(P₅₃₄)和667 kg/hm(P₆₆₇)］研究施肥量对枸杞产量与品质及土壤酶活性的影响，以期筛选出柴达木地区枸杞栽培的适宜施磷量。结果表明P₅₃₄处理枸杞的产量最高，为8 320 kg/hm，与P₆₆₇处理无显著差异。P₅₃₄处理枸杞总糖含量较P₀增加42.86%。P₅₃₄处理 0~100 cm土层土壤速效磷平均含量为28.9 mg/kg，较P₆₆₇处理提高5.63%， 0~40 cm土层速效磷平均含量较P₆₆₇处理增加14.26%。随施磷量的增加，土壤速效磷累积量呈先升后降趋势。0~20 cm及20~40 cm土壤磷酸酶活性最高为P₅₃₄处理，较P₆₆₇处理分别显著增加8.11%和11.65%。枸杞产量与0~20 cm土壤磷酸酶活性呈显著正相关，且与枸杞果实磷素累积量呈极显著正相关性。与农民习惯施磷量(667 kg/hm²)相比，P₅₃₄处理(减少20%的磷肥用量)能提高枸杞的产量、总糖、果实磷素累积量及0~40 cm土壤过氧化氢酶和磷酸酶的活性。综合评价，在柴达木地区高磷量枸杞园以施磷肥（P₂O₅）534 kg/hm² 为适宜施磷量。     

柔性机械式大豆精量排种器设计与试验

针对免耕播种作业时沙土和碎秸等飘浮物被气吸式排种器吸入充种室内，导致排种工作部件损坏、排种质量降低等问题，设计了一种柔性清护种机械式大豆精量排种器。对排种器工作过程进行理论分析，确定了影响工作性能的主要结构与工作参数；通过单因素对比试验确定了对排种性能影响最小的护种毛刷材料；采用三因素五水平二次正交旋转中心组合试验方法，以作业速度、充种倾角、护种距离为试验因素，以合格指数、漏播指数、重播指数和破损指数为评价指标，应用Design-Expert 8.0.6.1软件对试验结果进行方差分析。结果表明：各因素对合格指数的影响显著性由大到小依次为作业速度、护种距离、充种倾角，各因素对漏播指数的影响显著性由大到小依次为护种距离、作业速度、充种倾角，各因素对重播指数的影响显著性由大到小依次为作业速度、充种倾角，护种距离影响不显著，各因素对破损指数的影响显著性由大到小依次为护种距离、作业速度、充种倾角；当作业速度为8~12km/h、充种倾角70°、护种距离为-1.5mm时，排种合格指数大于94%、漏播指数小于3%、重播指数小于3%、破损指数小于0.2%，满足免耕大豆高速精量播种作业要求。     

The application of proximal visible and near-infrared spectroscopy to estimate soil organic matter on the Triffa Plain of Morocco

Soil organic matter (SOM) is a fundamental soil constituent. The estimation of this parameter in the laboratory using the classical method is complex time-consuming and requires the use of chemical reagents. The objectives of this study were to assess the accuracy of two laboratory measurement setups of the VIS-NIR spectroscopy in estimating SOM content and determine the important spectral bands in the SOM estimation model. A total of 115 soil samples were collected from the non-root zone (0–20 cm) of soil in the study area of the Triffa Plain and then analysed for SOM in the laboratory by the Walkley–Black method. The reflectance spectra of soil samples were measured by two protocols, Contact Probe (CP) and Pistol Grip (PG)) of the ASD spectroradiometer (350–2500 nm) in the laboratory. Partial least squares regression (PLSR) was used to develop the prediction models. The results of coefficient of determination (R²) and the root mean square error (RMSE) showed that the pistol grip offers reasonable accuracy with an R² = 0.93 and RMSE = 0.13 compared to the contact probe protocol with an R² = 0.85 and RMSE = 0.19. The near-Infrared range were more accurate than those in the visible range for predicting SOM using the both setups (CP and PG). The significant wavelengths contributing to the prediction of SOM for (PG) setup were at: 424, 597, 1432, 1484, 1830,1920, 2200, 2357 and 2430 nm, while were at 433, 587, 1380, 1431, 1929, 2200 and 2345 nm for (CP) setup.     

Inhibiting soil loss and runoff from small plots induced by an individual freeze-thaw cycle using three rangeland species

This study investigated the role of three rangeland species viz. Agropyron trichophorum, Medicago sativa, and Lolium prenne on mitigating of effects of a freeze-thaw (FT) cycle on runoff generation and soil loss from small experimental plots. Small plots (0.5 × 0.5m) were prepared in three replicates for control (i.e., under a FT cycle only) and treatments (i.e., individually planted with the study species and subject to a FT cycle). The treated plots were then placed at a slope of 20% and subjected to simulated rainfall with intensity of 70 mm h⁻¹ and 30 min duration. The results of the study showed a significant effect (P < 0.05) of the plants on controlling runoff and soil loss after a FT cycle. Also, the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the plants. Time to runoff increased by 54, 111 and 10%, runoff volume decreased by 27, 68 and 0.4% and soil loss changed by −34, −62, and +6.5% in the plots planted with A. trichophorum, L. prenne and M. sativa, respectively. The results of the current study indicated that L. prenne had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.     

Effect of time resolution of rainfall measurements on the erosivity factor in the USLE in China

Rainfall erosivity, one of the factors in the Universal Soil Loss Equation, quantifies the effect of rainfall and runoff on soil erosion. High-resolution data are required to compute rainfall erosivity, but are not widely available in many parts of the world. As the temporal resolution of rainfall measurement decreases, computed rainfall erosivity decreases. The objective of the paper is to derive a series of conversion factors as a function of the time interval to compute rainfall erosivity so that the R factor computed using data at different time intervals could be converted to that computed using 1-min data. Rainfall data at 1-min intervals from 62 stations over China were collected to first compute the ‘true’ R factor values. Underestimation of the R factor was systematically evaluated using data aggregated at 5, 6, 10, 15, 20, 30, and 60-min to develop conversion factors for the R factor and the 1-in-10-year storm EI₃₀ values. Compared with true values, the relative error in R factor using data at fixed intervals of ≤10min was <10% for at least 44 out of 62 stations. Errors increased rapidly when the time interval of the rainfall data exceeded 15 min. Relative errors were >10% using 15-min data for 66.1% of stations and >20% using 30-min data for 61.3% of stations. The conversion factors for the R factor, ranging from 1.051 to 1.871 for 5 to 60-min data, are higher than those for the 1-in-10-years storm EI₃₀, ranging from 1.034 to 1.489 for the 62 stations.