Effect of humic acid on growth and crop nutrient status of wheat on two different soils

The effect of plant-derived humic acid (PDHA) and coal-derived humic acid (CDHA) on wheat growth was tested on two alkaline calcareous soils in pots. Humic acid derived from plant and coal materials was applied at the rate 0 (control), 50 and 100 kg/ha to wheat in pots carrying two soils viz. clayey loam soil and sandy loam soil separately. Data was collected on plant growth parameters such as spike weight, grain and straw weight, and plant nutrients (macronutrients and micronutrients). Results showed that spike weight increased by 19%, 15%, and 26%, and 11% with application of PDHA at the rate of 50 and 100 mg/kg in clayey loam and sandy loam soil, respectively. Grain yield show an increase of 21% and 11% over control with application of PDHA and CDHA at the rate of 50 mg/kg on both soils, respectively, and 10% and 22% with application of PDHA and CDHA at the rate of 100 mg/kg on both soils.     

黏土和沙壤土对烟叶发育过程中栅栏细胞超微结构的影响

采用大田试验,比较研究了黏土和沙壤土烟叶发育过程中栅栏细胞超微结构变化,结果表明:1)叶长5 cm之前,黏土和沙壤土烟叶细胞超微结构变化差异不大.2) 5 cm之后沙壤土烟叶细胞发育较为迅速,叶长10～15 cm时叶绿体开始贴壁排列,功能开始全面发挥,叶长20 cm时基粒垛叠明显增厚,叶长30 cm时液泡发育成熟,叶绿体进入旺盛功能期;而黏土烟叶细胞发育相对迟缓,叶长20 cm时叶绿体功能才开始全面发挥,叶长40~50 cm时进入旺盛功能期.3)定长时黏土烟叶细胞内叶绿体积累的淀粉粒和嗜锇颗粒不及沙壤土烟叶充实.     

压砂西瓜间套马铃薯油葵栽培试验

针对宁夏压砂西瓜产业发展的需要,探索压砂西瓜高效栽培模式技术(间套)。结果表明:压砂西瓜套种油葵共生期长,前期油葵与西瓜争光和肥水,西瓜坐瓜和大小受限制,影响西瓜产量;压砂西瓜套种马铃薯共生期长,马铃薯与西瓜争光、争肥水不明显,西瓜坐瓜和大小不受限制,西瓜产量不受影响,每667 m2套种马铃薯生产比对照多收入231.2元。     

重非水相流体在砂壤中驱替与残留试验研究

通过对PCE在砂壤土中的人渗再分布以及水分驱替和残留的试验研究,结果表明:PCE在砂壤中的人渗与再分布深度和时间的关系可以很好地用对数函数来描述.水分驱替后被置换区域土壤内PCE的饱和度明显降低,向下迁移并累积,达到一定含量后,PCE向下运动锋面速率增大.被水置换后,PCE在土体内将残留一小部分,残留饱和度为4%～15%,多小于10%,随着容重增大残留量将增加,残留的PCE在土体中缓慢溶解,随水分类似于溶解的溶质进行对流和扩散,向上可能到达地表,挥发进入大气;向下则可能进入地下水体,成为长期的潜在污染源.     

Quantification of Organic Carbon in Soils: A Comparison of Methodologies and Assessment of the Carbon Content of Organic Matter

Abstract

Renewed interest in temporal soil organic carbon (SOC) stock changes has stressed the importance of reliable methods for quantitative assessment of organic compound (OC) content. Particularly with the establishment of modern dry‐combustion analyzers, which are replacing the traditional wet‐oxidation methods, the need for correct relationships between both is of crucial importance for comparison of past and current SOC data in long‐term SOC stock change studies. Dry combustion with a Variomax CNS‐analyzer was the standard to evaluate three other methods for Belgian agricultural soils. Excellent linear relationships were found with the Walkey and Black method and the Springer and Klee method, whereas a Shimadzu TOC‐analyzer slightly underestimated the OC content. Precision of the investigated methods was comparable and tended to be dependent on the sample size used for measurement. The OC oxidation efficiency of the most widely applied method of Walkey and Black for the soils in this study was very close to the generally accepted 75%. Mass loss on ignition at 800°C could be very well related to the soil OC content and the clay content. The traditional factor of 1.724 used to convert OC measurements to organic matter percentages is not valid for the investigated soils, which demonstrates that rather regional‐specific factors (in this study 1.911) should be determined and adopted.     

Effect of plastic-film mulching on leaching of nitrate nitrogen in an upland field converted from paddy

A lysimeter experiment was conducted to examine the effects of plastic film mulching on the leaching rate of nitrate nitrogen (NO₃-N) from chemical fertilizer that was applied to an upland field that had been converted from paddy rice production. Leaching was monitored in two lysimeters filled with sandy loam soil, which contained low soil organic matter content, under different surface mulch conditions. One was mulched only on the ridge (ridge-mulch treatment) and another one was mulched fully, including the furrow, with black plastic film (full-mulch treatment). Chemical fertilizer was mixed into the top 0.2 m of soil in the two lysimeters before installing the mulch. After transplanting broccoli, the amount of subsurface discharge water and the NO₃-N concentrations in the discharge water were measured every day. Larger NO₃-N discharges occurred in the ridge-mulch treatment for three days after heavy rainfalls in which cumulative precipitation exceeded 10 mm, and the daily NO₃-N load was twice as large as the full-mulch treatment. The differences in the amount of subsurface discharge water and NO₃-N discharged between treatments were not significant when there was no rainfall. Cumulative NO₃-N loads for the ridge- and full-mulch treatment during the last month of the experimental period were 0.246 and 0.195 g m^–2, respectively. The effect of mulching on the reduction of NO₃-N discharge rate was higher for the full-mulch treatment. This result showed that a plastic-film mulching system would be effective as an appropriate fertilizer management to reduce nitrate-leaching losses.     

Beta-carotene content of postharvest orange-fleshed muskmelon fruit: Effect of cultivar,growing location and fruit size

The influence of two growing locations (soil types), six fruit sizes, and two years on the postharvestBeta-carotene content of muskmelon (Cucumis melo L. var. reticulatus Naud.) fruit was studied with two different cultivars. Fully abscised commercial size fruit: 9, 12, 15, 18, 23, and 30 (fruit/0.04 M³ shipping box) had highly variableBeta-carotene contents (5.3 to 33.8 µg/g fresh weight) that varied by size class, soil type and cultivar.Beta-carotene content increased with fruit size up to a maximum, though fruit size continued to increase. Find sandy loam soil produced fruit with lessBeta-carotene content than silty clay loam soil. The cultivar Primo contained higherBeta-carotene content levels than cultivar Cruiser. Mesocarp percent moisture content for both Cruiser and Primo at both locations by fruit size was not significantly correlated (r=0.40) withBeta-carotene content. Indicating fruit cell dilution may not contribute to the differences inBeta-carotene content in different fruit size classes.Beta-carotene content of size class 18 fruit from six cultivars grown on the silty clay loam soil for two consecutive years, showed a year, and year by cultivar effect for some cultivars. Whereas, some cultivars did not differ inBeta-carotene content between the two years. This indicates a potential for controllingBeta-carotene content of muskmelon fruit at a constant, high level by careful selection of production cultivar.Mention of a trademark of propriety does not constitute a guarantee or warranty of the product by the US Department of Agriculture or Texas A&M University and does not imply its approval to the exclusion of other products that also may be suitable.     

Improvement of paddy field drainage for mechanization

In Japan, land consolidation and drainage improvement for farm mechanization in paddy fields began during the 1960 s. It was not easy to use big machines in the muddy conditions caused by the clayey soil and heavy rainfall during the harvesting period. A number of investigations were carried out by many researchers, and factors relating to drainage were clarified. Not only surface drainage but also underdrainage was planned. However, drainage was not always sufficient, because the clayey surface soil was impermeable to ponding water. It became clear that underdrainage for a clayey paddy field for the harvest is quite different from underdrainage for an ordinary field. Field and soil characteristics, as well as water conditions, should be examined carefully before planning drainage improvement for farm mechanization.Dr. Toshio Tabuchi is an honorable member of the Japanese Society of Irrigation, Drainage and Reclamation Engineering (JSIDRE), a former Professor of the University of Tokyo, and a former President of JSIDRE     

A new method for studying clay soils using unaltered soil blocks

The purpose of this paper is to outline a procedure for soil block extraction, which is highly appropriate for clay soils. The method described here is rapid and cheap and has been used successfully by us in clay soils in southern Spain for the last six years. A wooden box is used to shape the soil block in situ and protect it during its transport from the field to the laboratory. Polyurethane foam was selected as the bonding agent, between the wooden framework and the soil block in order to avoid any possible alterations of the soil. This type of foam is used because it is strong, durable and non-toxic. The polyurethane foam is applied to the soil block as a permanent coating. This technique allows us to extract the clay soil solution in the laboratory.