保水材料对河套灌区土壤硝态氮和铵态氮动态变化的影响

为了研究内蒙古河套灌区农业化肥面源污染检测和治理措施,采用大田土壤淋溶试验,分析了河套灌区农田在保水材料处理下,玉米生育期内土壤硝态氮、铵态氮累积量及动态变化特征。结果表明,与CK相比,保水材料处理玉米苗期土壤NO_3~--N累积量平均提高20.49%,收获期平均降低13.98%;苗期土壤NH_4~+-N累积量平均提高35.21%,收获期平均降低28.93%。保水材料有效地抑制了氮素的淋溶损失,提高了氮素利用率,同时保证了玉米生育后期有效氮的供应,避免短时间内氮素的大量累积,在一定程度上减少了化肥面源污染,为农业面源污染治理提供有力措施。     

Laboratory vs. in situ resin‐core methods to estimate net nitrogen mineralization for comparison of rotation and tillage practices

Properly estimating soil nitrogen (N) mineralization as a consequence of different agronomic practices would result in better soil N fertility management. In this study, we tested the differences between laboratory and in situ resin‐core incubation methods for estimating soil net N mineralization for long‐term burley tobacco (Nicotiana tobacum L .) tillage and rotation systems. The laboratory incubation method used crushed, homogenized, litter‐free soil samples, and the in situ resin‐core incubation method used an intact soil core with the inclusion of any plant residue below or above ground. Comparisons showed that no‐tillage had significantly increased soil net N mineralization compared to conventional tillage with the laboratory incubation method, while there was no significant difference between tillage methods with the in situ resin‐core method. This indicates that soil pretreatment in the laboratory incubation method can create an “artificial tillage effect” for soil previously managed with no‐tillage, resulting in overestimated soil net N mineralization. The rotation comparison showed that different crop sequences had no impact on measured net N mineralization with the laboratory incubation method. However, a preceding soybean crop did significantly increase net soil N mineralization compared to preceding corn when measured with the in situ resin‐core method. This suggests that discarding plant residue in the laboratory incubation method can neglect the potential effect of plant residue on soil N mineralization. Therefore, it is important to be aware that soil pretreatment may influence soil N mineralization estimates, potentially resulting in flawed decisions for soil N fertility management.     

几种农作物对绿黄隆敏感性的生物测定及在残留检测中的应用

采用土壤添加培养的方法测定了绿黄隆对玉米、水稻、大豆等作物的生物活性。结果表明 :绿黄隆在土壤中对玉米的致害阈限 ( IC1 0 )为 0 .1 7μg/ kg,对水稻的致害阈限则为 0 .4 3 4 9～ 0 .94 1 0μg/ kg,同时 ,绿黄隆的代谢产物之一的邻氯苯磺酰胺对玉米的生物活性要比绿黄隆的低得多 ,它对以玉米根系鲜重为指示指标的生物测定方法不会产生干扰 ,确定了以玉米根系鲜重为指示指标的生物测定方法 ,并以此得到了标准方程 ( P=4 .6653 1 .0 2 3 5lg C,r=0 .9859* * ) ,用该方法检测了田间连续 2年使用绿黄隆后土壤中的残留量。检测结果表明 :第 1年使用 ,6个月后土壤中绿黄隆的残留量约为施药当日的 1 0 %左右 ;连续 2年使用 ,土壤中的残留量较上一年略有增加     

人造板企业减少锅炉SO2排放的途径

介绍了减少锅炉SO2排放的基本途径与主要方法,重点分析了这些方法在人造板企业的适用性.     

银杏叶类胡萝卜素的研究

银杏叶和提取黄酮(GBE)生产过程中的废弃物含有的类胡萝卜素主要为叶黄素、紫堇新质、隐黄质、新黄质和其他胡萝卜素,是天然的着色剂,如能加以利用,是银杏产业资源综合利用和循环经济发展的途径之一。     

喹胺醇在鸡组织的消除及残留研究

以鸡为靶动物,多次口服(50 mg/kg,每12 h 1次,连续6次)喹胺醇,测定其在肝脏、肾脏及肌肉中的残留.用乙腈-乙酸乙酯(3/2,V/V)提取组织中的药物,反相高效色谱法测定组织中喹胺醇的浓度.色谱条件:C18-ODS柱(25 ㎝×4 .6),流动相为乙腈:水(2/3,V/V);流速1.0 ml/min,紫外检测波长为334 nm.鸡多次口服喹胺醇,于第6次给药后在肝脏、肾脏、肌肉药物的消除半衰期为5.91、6.489、5.727 h.若规定组织中喹胺醇浓度最高残留限量为1ng/g可食用,则休药期应为2天.     

JMPR 农药残留急性膳食摄入量计算方法

农药残留急性膳食风险评估直到最近才引起大家的关注。目前，粮农组织和世界卫生组织农药残留联席会议（JMPR）研究国际范围农药急性膳食风险评估；美国、英国、荷兰、澳大利亚和新西兰也开始进行国家农药急性膳食风险评估。农药急性膳食风险是急性或短期接触毒性与农药急性膳食摄入量的函数。急性膳食接触量评估常用的方法有：定点或确定性方法和概率模型法。在确定性方法中选取食物的大部分人群消耗量和高残留量来计算膳食摄入量，为了解决混合样品中食品个体之间的残留差异，在计算中引入了变异因子。JMPR根据具体情况分为情形1、情形2a、情形2b、情形3来计算农药急性膳食摄入量。中国应该尽快建立健全膳食结构和农产品性状数据库，建立健全市场中农产品的农药残留数据库，并在高毒和中等毒性农药登记前应采用JMPR的确定性方法，进行急性膳食风险评估，提高农药膳食摄入的安全性。     

厩肥、秸秆和绿肥的含钾状况及其对土壤和作物钾素的供应能力

以常用有机肥料牛厩肥、猪厩肥、鸡粪及作物秸秆、油菜绿肥为材料，研究了这些有机物的全钾、速效钾和缓效钾的含量状况，以及它们对土壤钾及作物吸钾的供应能力。结果表明：（１）三种有机烘肥及作物秸秆、绿肥中含钾量为０．８５％～４．５０％，其中有３２．７％～６９．７％为速效态钾，１．７％～２５．０％为缓效态钾；（２）肥料与土壤共同培养１５０ｄ后，约有５０％～８０％的速效态钾和缓效态钾仍以两种形态存在于土壤之中     

The effect of lupins as compared with peas and oats on the yield of the subsequent winter barley crop

New high yielding early maturing cultivars of lupins have been introduced in north-west Europe as grain protein crops in crop rotations. This paper reports on a comparative study of lupins with peas and oats, and of their effect on yield of subsequent winter barley crops. These crops were given five levels of N under irrigated and non-irrigated conditions on sand and loam. Under rain fed conditions the grain yield of pea, oat and lupin varied between 24–36, 34–53 and 18–37 hkg DM ha⁻¹, respectively. Supplemental irrigation raised grain yield of oat to 50–60 hkg DM ha⁻¹, while grain yield in pea was not affected and grain yield in lupin in most cases decreased due to gray mould attack and excessive vegetative growth in the indeterminate lupin variety. Under rain fed conditions, the grain nitrogen content of pea, oat and lupin varied between 137–172, 61–80 and 189–226 kg N ha⁻¹, respectively, and was significantly higher in lupin as compared with pea. On sandy soil, similar low-root densities were found for pea, oat and lupin below 30 cm depth. On sand, at final harvest the residual soil-N of lupin and pea, as measured in a subsequent winter barley crop not supplied with N fertilizer, was 15 and 8–10 kg N ha⁻¹ higher than in winter barley following oat, respectively. The nature of the probably more N-root residues of lupin is discussed. On loam, the residual N of lupin and pea was similar, 18–27 kg N ha⁻¹. On sand, under rain fed conditions preceding lupin and pea as compared with oat, increased the barley grain yield at zero N-application 77 and 49%, respectively; the effect of lupin was significantly higher than that of pea until the highest N-level 120 kg N-application ha⁻¹. On loam under rain fed conditions preceding lupin and pea increased the barley grain yield at zero N-application by 36 and 62%, respectively, as compared with oat; at N-application>60 kg N ha⁻¹ the grain yield was similar after all three crops. For both soil types the same level of effect was found under irrigated conditions. Conclusions: Supplemental irrigation might result in lower grain yield in lupin due to gray mould attack and excessive growth if indeterminate lupin varieties are used. Grain nitrogen yield of lupin is significantly higher than that of pea. On sand, the effect of lupin on the subsequent winter barley grain yield is significantly higher than that of pea, probably due to greater N-root nitrogen residues. On loam, lupin and pea have similar effects on the subsequent winter barley crop.     

Chemical composition controls residue decomposition in soils differing in initial pH

Laboratory incubation studies were conducted to determine the dynamics of low-molecular-weight aliphatic carboxylic acids and their anions (LACAs) and respiration in three soils incorporated with five types of plant residues differing in chemical composition. Concentrations of total and individual LACAs in soils decreased sharply with initial 3 days after addition of plant residues, and varied with types of plant residue and soil. Irrespective of soil types, the amount of total extractable LACAs was highest in the soils treated with chickpea, followed by lucerne and high-N wheat straw, and lowest with low-N wheat straw. Lancelin soil [initial pH(CaCl₂) 5.06] contained higher concentration of extractable LACAs compared with Bodallin (pH 4.54) and Wodjil soil (pH 3.87). Soil respiration rate was rapidly increased by the addition of plant residues, and reached the peak by Day 3. Respiration rate was the greatest in Lancelin soil and the smallest in Wodjil soil. The amounts of CO₂ respired over 7 days were equivalent to 6-25% of the added C for Wodjil soil, 6-39% for Bodallin soil and 6-47% for Lancelin soil, depending on type of plant residue. Those amounts over 105 days increased further. Irrespective of plant residue and soil type, the cumulative respiration correlated positively with concentrations of N, excess cations and soluble C in plant residues and initial soil pH, and negatively with C:N of plant residues. The results suggest that chemical composition of plant residues plays an important role at the initial stage of residue decomposition.