Impact of pig slurry on soil properties, water salinization, nitrate leaching and crop yield in a four-year experiment in Central Spain

Abstract. The repeated application of pig slurry to agricultural soils may result in an accumulation of salts and a risk of aquifer pollution due to nitrate leaching and salinization. Under Mediterranean conditions, a field experiment on a sandy loam soil (Typic Xerofluvent) was performed with maize (Zea mays) in 1998, 1999 and 2001 to study the effects of applying optimal (P1) and excessive rates (P3) of pig slurry on soil salinization, nitrate leaching and groundwater pollution. The rate of pig slurry was established considering the optimal N rate for maize in this soil (170, 162 and 176 kg N ha^?1 for 1998, 1999 and 2001, respectively). Pig slurry treatments were compared to an optimal N rate supplied as urea (U) and a control treatment without N fertilizer (P0). The composition of the slurries showed great variability between years. Mean NO₃^? leaching losses from 1998 to 2001 were 329, 215, 173 and 78 kg N ha^?1 for P3, P1, U and P0 treatments, respectively. The amount of total dissolved salts (TDS) added to the soil in slurry application between 1998 and 2001 was 2019 kg TDS ha^?1 for the P1 treatment and 6058 kg TDS ha^?1 for the P3 treatment. As a consequence, the electrical conductivity (EC) of the slurry‐treated soils was greater than that of the control soil. The EC correlated significantly with the sodium concentration of the soil solution. Over the entire experimental period, 2653, 2202 and 2110 kg Na ha^?1 entered the aquifer from the P3, P1 and P0 treatments, respectively. The P3 treatment did not significantly increase grain production in 1999 and 2001 compared with that achieved with the optimal N rate treatment (P1). This behaviour shows the importance of establishing application guidelines for pig slurry that will reduce the risk of soil and groundwater pollution.     

淡紫拟青霉发酵滤液对大豆胞囊线虫趋化性的影响

 实验室条件下,研究了大豆胞囊线虫幼虫对大豆根和根浸出液的趋化性以及淡紫拟青霉代谢产物对其趋化性的影响。结果表明,大豆胞囊线虫二龄幼虫(J₂)对大豆根存在着一定的趋化性,而淡紫拟青霉发酵滤液对J₂存在明显的驱避性。在根浸出液、真菌滤液及其混合液剂处理下,大豆胞囊线虫J₂在WA平板上靠近处理液的0~1cm区间中分布率存在极显著差异(P <0.0 1),而加样时间(液剂与线虫同时放置或提前2 4h处理)对其分布率没有显著影响。大豆幼根蘸取滤液后对线虫J₂在该区间的分布与不经处理的幼根差异显著(P <0.0 5),证明淡紫拟青霉发酵滤液可以明显地降低线虫与大豆根的亲和力,并强烈抑制线虫对大豆根的侵染。     

一株Fusarium oxysporum f. sp. niveum拮抗菌的筛选、鉴定及其抑菌特性

为筛选西瓜枯萎病拮抗菌株并探究其抑菌特性,以齐齐哈尔市青昕蔬菜基地根际土为材料,采用平板对峙法筛选到1株能高效抑制西瓜专化型尖孢镰刀菌(Fusarium oxysporum f.sp. niveum,Fon)的拮抗菌株,通过形态特征、16S rDNA、gyrA和gyrB序列分析鉴定其菌种;通过盆栽试验验证拮抗菌株对西瓜枯萎病的抑制作用;采用生长速率法研究拮抗菌株不同生长时期的无菌发酵滤液及其不同贮存条件下的抑菌能力;利用扫描电子显微镜(SEM)和共聚焦激光扫描显微镜(CLSM)观察并分析无菌发酵滤液对Fon孢子形态和膜完整性的影响。结果表明,拮抗菌株WD为Bacillus amyloliquefaciens,能有效抑制西瓜枯萎病的发生,抑制率达到57.57%,其无菌发酵滤液在衰亡期有较高的抑菌能力,对Fon菌丝生长抑制率为54.32%;无菌发酵滤液对温度、pH具有较高的耐受性,30 ℃、pH 7时抑菌活性最强,抑菌率可达58.36%;在4 ℃贮存至少45 d,且紫外光照120 min内对其抑菌活性没有影响;Fon孢子暴露在WD无菌发酵滤液下,孢子表面皱缩凹陷,膜完整性被破坏。综上所述,Bacillus amyloliquefaciens WD是1株高效的拮抗菌株,为西瓜枯萎病生防菌剂的研发与利用奠定了基础。     

Effects of cover crop growth and decomposition on the distribution of aggregate size fractions and soil microbial carbon dynamics

Although the effects of cover crops (CC) on various soil parameters have been fully investigated, less is known about the impacts at different stages in CC cultivation. The objective of this study was to quantify the influence of CC cultivation stages and residue placement on aggregates and microbial carbon (C_mic). Additionally, the influence of residue location and crop species on CO₂ emissions and leached mineralized nitrogen (N_min) during the plant degradation period was also investigated. Within an incubation experiment, four CC species were sown in soil columns, with additional columns being kept plant‐free. After plant growth, the columns were frozen (as occurs in winter under field conditions) and then incubated with the plant material either incorporated or surface‐applied. With CC, concentrations of large and medium macroaggregates were twice that of the fallow, confirming positive effects of root growth. Freezing led to a decrease in these aggregate size classes. In the subsequent incubation, the large macroaggregates decreased far more in the samples with CC than in the fallow, leading to similar aggregate size distributions. No difference in C_mic concentration was found among the CC cultivation stages. CO₂ emissions were roughly equivalent to the carbon amounts added as plant residues. Comparison of columns with incorporated or surface‐applied residues indicated no consistent pattern of aggregate distribution, CO₂ emission or C_mic and N_min concentrations. Our results suggest that positive effects of CC cultivation are only short term and that a large amount of organic material in the soil could have a greater influence than CC cultivation.     

复配材料超声处理对化肥控失效果的影响

利用超声波对化肥控失材料(LCM)进行修饰改性,结果表明对硫酸铵的控失效果随处理时间呈现先升高然后降低的规律,峰值出现在5min.本文对其机理进行初步探讨.     

AN APPRONTMATE CALCULATING METHOD FOR WALL PLATES OF MAN'' S DRY GAS HOLDERS

The basic equations of wall plates of MAN' S dry gas holders are derived in this paper. According to the law of cylindrical bending given by the finite element results .we derive some approximate formula calculating the deflection and stresses of the wall plates from the basic equations. Compared with the known approximate calculating method.the method car. obviously increase the percision.     

THE PERFORMANCE ANALYSIS FOR THE HYDRAULIC SERVO-SYSTEM OF HAULAGE PARTY FOR SGW-150 SHEARER WITH CONSTANT POWER SPEED GOVERING

The mechanization of mining thinnest coal seam is a key program in the 7th five-year plan in Sichaan province, It is sponsored by The Scientific and Technieal Commission of Sichuan province. In this paper, the dynamic performance for the hydraulie servo-system of haulage party for SGW-150 shearer with coustant-power speed governing is analysed. It shows that the system designed by us is stability and reasonable for SGW-150 shearer.     

Studies on the Oxidation of Weathered Coal with Nitric Acid

A raseach has been done on the possibility of producing nitriochumic acid fromweathered coal of Nantong,Sichuan,oxidised by nithic acid.The optimun reacting conditions,whichare found through the way of orthogonal experiment,are suggested as follows:concentration ofHON3 35%,rate of HON3 to coal 3.5,reacting take 15 min,and reaction temperature 369 K. Thecomposition of product is Wf 2. 91 %;Ag 14.06%;HAg 78.28%;Ng 1.62%.