An economic evaluation of site-specific herbicide application

The objective of this study was to determine if site-specific application of postemergence herbicide was economically viable with current technologies. This objective was accomplished by: developing an algorithm that determined the economic optimal postemergence herbicide rate; creating models to determine the impact that postemergence herbicide rate has on yield; and determining whether site-specific application of postemergence herbicide has greater net returns than those from a uniform application of postemergence herbicide. Weed species identification and population counts were done on a regular grid in five fields across Kansas. A decision algorithm was developed to determine the economic optimal rate of postemergence herbicide for each grid cell. The site-specific herbicide rate and four standard herbicide rates [0, 0.5, 0.75, and full (1×) label rate] were applied according to a split-plot design. Weed population observations made three weeks after application showed that the site-specific treatment controlled the weeds present in the fields. Production functions developed to determine whether postemergence herbicide rate had an impact on yield showed that it had a positive, yet statistically insignificant, effect on yield. The difference in estimated net returns between applications of site-specific rate and uniform full-label rate covered all of the costs associated with site-specific application of postemergence herbicide. The margin between the estimated net returns for site-specific and uniform application of the economic optimal rate covered only a portion of the costs associated with site-specific application of postemergence herbicide.     

Canopy-air temperature differential for potato under different irrigation regimes

Abstract

The main objective of this study was to determine canopy-air temperature differential, which can be used to quantify crop water stress index (CWSI) for potato. The crop was cultivated under furrow irrigation and subjected to three irrigation regimes in which irrigation was applied when 30, 50 and 70% of the available water holding capacity was consumed, and three irrigation levels (100, 50 and 0% replenishment of soil water depleted). The highest yield and water use was obtained under non-water-stressed treatments (100% replenishment of soil water depleted) for each irrigation regime. The lower (non-stressed) and upper (stressed) baselines were determined empirically from measurements of canopy temperatures, ambient air temperatures and vapour pressure deficit values and the CWSI was calculated with three irrigation levels for each irrigation regime. Trends in CWSI values were consistent with the soil water contents induced by the deficit irrigations. Average CWSI before irrigation values of 0.49 for irrigation when 30% of the available water holding capacity was consumed, 0.55 for irrigation when 50% of the available water holding capacity was consumed and 0.69 for irrigation when 70% of the available water holding capacity was consumed, produce maximum tuber yield. The yield was also directly correlated with seasonal CWSI values.     

Widespread Deficiencies of Sulfur,Boron, and Zinc in Indian Semi-Arid Tropical Soils: On-Farm Crop Responses

On-farm studies were conducted during 2002–2004 to determine fertility status, including sulfur (S) and micronutrients, and crop response to fertilization on farmers' fields in the semi-arid zone of India. Nine hundred-twenty four soil samples taken from farmers' fields, spread in the three districts of Andhra Pradesh (India), were analyzed for soil chemical fertility parameters. Results showed that samples were low in organic carbon (C), total nitrogen (N), and low to moderate in extractable phosphorus (P), but adequate in available potassium (K). Analyses of soil samples for extractable S and micronutrients was most revealing and showed that 73–95% of the farmers' fields were deficient in S, 70–100% in boron (B), and 62–94% in zinc (Zn). On-farm trials conducted during three seasons (2002–2004) showed significant yield responses of maize, castor, groundnut, and mung bean to the applications of S, B, and Zn. The yield responses were larger when S, Zn, and B were applied along with N and P. Applications of S, B and Zn also significantly increased the uptake of N, P, K, S, B, and Zn in the crop biomass. Results show widespread deficiencies of S, B, and Zn under dryland agricultural conditions; results also show that the nutrient deficiencies can be diagnosed by soil testing. It was concluded that the drylands in the semi-arid regions of India were not only thirsty (water shortage), but also hungry (nutrient deficiencies).     

Determination of actual evapotranspiration and crop coefficients of broad bean (Vicia Faba L.) grown under field conditions in the jordan valley,jordan: Bestimmung der aktuellen evapotranspiration und pflanzenbestandskoeffizienten von bohnen (Vicia Faba L.) unter feldbedingungen im jordantal,jordanien

This study was conducted to determine actual evapotranspiration and crop coefficients at different growth stages of broad bean (Vicia faba L.) grown in an open field in the Jordan Valley, Jordan using a precise and accurate approach. The study involved 30-min fluxes measurements of energy budget components over broad bean crop using a complete setup of an Eddy Correlation (EC) system. The measurements were conducted during the three main crop growth stages namely initial, development, and midseason growth stages following the Food and Agriculture Organization of the United Nations (FAO) crop coefficient model for green harvested broad bean crop. The average crop coefficients during the initial (K_{C ini}), development (K_{C dev}) and midseason (K_{C mid}) growth stages were 0.37, 0.8 and 1.05, respectively. The measured weighted average crop coefficient over the entire growing season K_{C GS} was 9.5% lower than the FAO corresponding value.

Results showed that there was a clear decrease of (bulk) surface resistance (r_s) as crop canopy developed. Daily average r_s values were 855, 337, and 166?s/m for initial, development, and midseason growth stages, respectively. Moreover, r_s was found to be highly correlated to crop height (h_c). A simple linear relation between r_s and h_c with R² of 0.91 was found. This relation will enable future direct determination of crop evapotranspiration (ET_C) using Penman-Monteith equation without the need to calculate both grass reference evapotranspiration (ET_O) and crop coefficient (K_C) values.     

农业保险促进了土地流转吗?——基于华中三省的实证分析

农村土地“三权分置”虽然为土地流转提供了制度保障,但农业经营规模的扩大仍会带来各类风险。农业保险能在一定程度上降低投保农户的风险损失,因此可能会对农户的土地流转行为产生影响。本文基于华中三省1045名从事农作物生产农户的调研数据,探究农业保险对土地流转行为的影响。研究发现,虽然流入土地的农户会有更大的可能性参保,但农业保险并没有促进土地流转,推测是因为农业保险保障水平较低,不足以促进一般农户扩大经营规模。异质性分析指出,农业保险确实促进了高收入农户的经营规模扩大。本研究结果表明低保障水平的农业保险虽然满足了规模经营农户的风险保障需求,但对土地流入和规模扩大的促进作用仍然有限。     

黄土母质生土地不同施肥对作物产量的影响

研究表明不论深层生土或浅层生土，当年施用足够量的氮磷钾配合肥，特别是与一定量有机肥配合都可较对照生土不施肥成倍地提高产量，生土地上单独施用不同肥料效果甚低，其对产量影响的排序为：有机肥＞Ｐ＞Ｋ或Ｎ，Ｎ与Ｋ差异不大，生土地施用黑矾无明增产效果。     

湖北省农作物种植结构区划

采用定性与定量相结合的方法,利用湖北省近5年来农作物播种面积数据以及相关的自然、社会、经济数据,对湖北省农作物种植结构进行区划。将湖北省农作物分为2级区划,包括鄂东南低山丘陵湿润水稻主作区、鄂北低山丘岗半湿润水旱兼作区、鄂西北山地半干旱旱作物区、鄂中平原半湿润水旱兼作区、鄂西南山地湿润水旱兼作区等5个一级区划分区和武鄂黄蔬菜-水稻-油料作区等13个二级区划分区。     

生物有机肥在水稻等农作物上的肥效试验

[目的]为了研究生物有机肥在水稻等农作物上的肥力效应。[方法]对两优培九中稻、荔浦芋、黑皮果蔗、大白菜和西瓜进行生物有机肥施用效果研究。[结果]结果表明:施用生物有机肥,果实增产显著,品质大有改观,甜度增加,口感好。[结论]该研究为生物有机肥的推广应用提供了依据。     

文献导读模式在作物育种学“课程思政”中的应用

“课程思政”是习近平总书记关于教育论述的重要内容之一,但农学专业课“课程思政”在落实高校立德树人根本任务方面的功能性还未充分体现。针对农学专业人才培养现状,以作物育种学为例,采用文献导读教学方法将“多样化”“隐性化”“特色化”的思政元素融入课程,探索文献导读在作物育种学“课程思政”中的应用模式,发挥农学专业课程在“德育”和“智育”方面的作用,并为农学专业课“课程思政”建设提供参考。     

杂种稻的光合适应性及光合生产力研究

 用不同光强生态型水稻品种Lemont和七桂早，利用化学杂交剂配制得杂种稻Le／七。对Le／七及其亲本在人工气候箱中高、低光强条件下处理30 d，每10 d作一次光合测定及生长分析。量子产量和单叶净光合速率的测定结果表明：Le／七对高、低光强的适应范围比双亲有所扩大，尤其是在高光强下量子产量相对降低值Le／七比七桂早明显为低。处理期间杂种Le／七比七桂早明显为低。处理期间杂种Le／七的光合生产力(以作物生长率CGR表示)和生物学产量增加值在高、低光强条件下均明显超过了其父本广东当地优良品种七桂早，其CGR和生物学产量高的主要原因是其叶面积指数(LAI)、净同化率(NAR)由于杂种优势比七桂早明显为高。