Tillage and Landscape Position Effects on Soil Properties and Crop Production

The management problems associated with utilizing a single cropping system across an undulating landscape that contains well and poorly drained soils were addressed. Results from this work will aid farmers in making their tillage and crop rotation decisions. Four tillage treatments (moldboard plow, chisel plow, ridge-till and no-till) and three cropping sequences (continuous corn, corn after soybean, and soybean after corn) were arranged in a split plot design on a well drained Beadle and poorly drained Worthing soils. Worthing soil surface has a signlficant1y lower hydraulic conductivity and higher volumetric moisture, pH, available phosphorus and potassium than the Beadle soil. Crop emergence and grain yield were significant1y reduced in the Worthing soil compared to the Beadle soil across all tillage systems. Ridge-till and no-till treatments behaved differently from mdldboard and chisel plow treatments with respect to overall physical properties in the Beadle soil. Ridge-till and no-till plots had significantly higher volumetric moisture, lower soil temperature and higher bulk density than the moldboard plow and chisel plow plots. No significant difference in water use (evapotranspiration) was observed between tillage treatments in either soil. Little difference in physical properties of the Worthing soil was observed due to tillage except for a higher bulk density in the ridge and no-till treatments than other tillage treatments. Few differences in chemical properties due to tillage systems were found in these soils. A significantly higher pH was observed in the moldboard plow and chisel plow Beadle plots than in the ridge-till and no-till plots. Ridging in the Worthing soil significantly increased nitrate levels at 0-0.60 m compared to chiseling and no-till treatments. Little difference in crop development and grain yield was observed in either soil due to tillage in 1986. Moldboard plowed Beadle plots under continuous corn produced significantly higher leaf area most of the growing season and grain yield than other tillage treatments in 1987. Moldboard plow behaved differently from other treatments with respect to agronomic parameters in the Worthing soil in 1987 due to delayed plowing and the resulting cloddy surface. Ridge-till or no-till systems with corn-soybean rotations were found to be the best cropping systems practices in fields comprised of different proportions of well and poorly drained soils

Site-specific seeding using multi-sensor and data fusion techniques : a review

Site-specific seeding (SSS) is a precision agricultural (PA) practice aiming at optimizing seeding rate and depth, depending on the within field variability in soil fertility and yield potential. Unlike other site-specific applications, SSS was not adopted sufficiently by farmers due to some technological and practical challenges that need to be overcome. Success of site-specific application strongly depends on the accuracy of measurement of key parameters in the system, modeling and delineation of management zone maps, accurate recommendations and finally the right choice of variable rate (VR) technologies and their integrations. The current study reviews available principles and technologies for both map-based and senor-based SSS. It covers the background of crop and soil quality indicators (SQI), various soil and crop sensor technologies and recommendation approaches of map-based and sensor-based SSS applications. It also discusses the potential of socio-economic benefits of SSS against uniform seeding. The current review proposes prospective future technology synthesis for implementation of SSS in practice. A multi-sensor data fusion system, integrating proper sensor combinations, is suggested as an essential approach for putting SSS into practice

Sensitivity of EM38 in determining soil water distribution in an irrigated wheat field

Geonics EM38 is a portable, non-invasive equipment that induces an electrical current in the soil for rapid measurement of apparent electrical conductivity (ECa) in the field. We used an EM38 in a wheat field to evaluate the effects of systematic variation in soil water content (within three replicate plots of four irrigation treatments) and seasonal variation in soil temperature on ECa. The effective depth of sensing of EM38 could be varied by using it in both vertical and horizontal dipole modes and by placing it at various heights above the ground. Accumulated water within various soil depths was measured with a neutron probe throughout the season. Values of ECa over the season for a soil depth related linearly or nonlinearly with soil water within that depth with a coefficient of determination (R2) of 0.70-0.81. ECa values were also influenced by variation in soil temperature within 5-25 cm depth (range 10.1-29.3 C) and air temperature (range 14.2-34.0 C), but to a smaller extent than soil water. The overall relationship between ECa, soil water and soil temperature improved considerably when multiple regression was used (R2 = 0.82-0.98). Good correspondence between maps of ECa and soil water content over the experimental field suggests that ECa maps could be useful in determining spatial distribution of soil water within crop fields so that variable rather than uniform quantity of irrigation water can be applied to improve water use efficiency

Eight-year experience in esophageal cancer surgery

Aim: Esophageal cancer remains a major and lethal health problem. In Nepal, not much has been explored about its management. The aim of this study was to conduct a retrospective review of esophageal cancer patients undergoing surgery or combined modality treatment at a cancer hospital in Nepal. Materials and Methods: Resectable cases were treated primarily with surgery. Locally advanced cases with doubtful or obviously unresectability underwent preoperative chemo/radiation or chemoradiation followed by surgery. Results: Among 900 patients, 103 were treated with curative intent. Mean age of patients was 54 years, and 100% of the patients presented with complaint of dysphagia. Surgery as a single modality of treatment was done in 57% of cases, and the remaining underwent combined modality treatment. Transthoracic and transhiatal approaches were used in 95% and 5% of cases, respectively. Nodal sampling, two-field (2-FD), and three-field lymphadenectomy (3-FD) were done in 18%, 59%, and 20% of cases, respectively. A majority of patients had pathological stage III disease (46.6%). In-hospitality mortality was 5%, and anastomotic leakage rate was 14%. In 87% of patients, R0 resection was achieved. Overall, 4-year survival was 20%. A R0 resection, early-stage disease and 3-FD favored the survival advantage (P < 0.05). Conclusion: The mortality, complication, and survival results were in the acceptable range. R0 resection and radical nodal dissection should be standard practice

Eight-year experience in esophageal cancer surgery

Aim: Esophageal cancer remains a major and lethal health problem. In Nepal, not much has been explored about its management. The aim of this study was to conduct a retrospective review of esophageal cancer patients undergoing surgery or combined modality treatment at a cancer hospital in Nepal. Materials and Methods: Resectable cases were treated primarily with surgery. Locally advanced cases with doubtful or obviously unresectability underwent preoperative chemo/radiation or chemoradiation followed by surgery. Results: Among 900 patients, 103 were treated with curative intent. Mean age of patients was 54 years, and 100% of the patients presented with complaint of dysphagia. Surgery as a single modality of treatment was done in 57% of cases, and the remaining underwent combined modality treatment. Transthoracic and transhiatal approaches were used in 95% and 5% of cases, respectively. Nodal sampling, two-field (2-FD), and three-field lymphadenectomy (3-FD) were done in 18%, 59%, and 20% of cases, respectively. A majority of patients had pathological stage III disease (46.6%). In-hospitality mortality was 5%, and anastomotic leakage rate was 14%. In 87% of patients, R0 resection was achieved. Overall, 4-year survival was 20%. A R0 resection, early-stage disease and 3-FD favored the survival advantage (P &lt; 0.05). Conclusion: The mortality, complication, and survival results were in the acceptable range. R0 resection and radical nodal dissection should be standard practice