This thesis examined the effect of continuous row-cropping on soil structure measured by bulk density and compaction ratings. Undisturbed core samples were collected from the selected sample sites to determine the bulk density. Compaction ratings were obtained by using a Proctor Penetrometer. A total of 192 soil samples were collected for this investigation. Comparisons of mean bulk densities, mean compaction ratings, and mean moisture percentages of the surface and Bt horizons of Blount and Pewamo soils in Delaware County, Indiana under three different field conditions: woods (untilled), field cultivated fields (continuous row-cropped), and plowed fields (continuous row-cropped) were made. This was done by calculating F-ratios and Bayesian Least Significant Difference ratios. Pearson's Product Moment Correlation' Coefficients were also calculated between selected parameters of the data. Conclusions drawn from these statistical analysis were discussed.

Thesis (Ph.D.)--Industrial and Systems Engineering, Georgia Institute of Technology, 2007. / Committee Co-Chair: Griffin, Paul; Committee Co-Chair: Serban, Nicoleta; Committee Member: Liang, Steven; Committee Member: Sharp, Gunter; Committee Member: Tsui, Kwok-Leung

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Maize (Zea mays L.) is one of the most important crops in South Africa that is cultivated for food, feed and as a cash crop. Maize in the Eastern Cape is typically grown for consumption and the Province is one of the least producers owing to small landholdings, poor production conditions and pests. This study investigated: (i) the different maize cropping systems smallholder farmers practice in the Eastern Cape (EC), (ii) the major maize insect pests within the identified cropping systems, (iii) the perceptions of Eastern Cape smallholder maize farmers on the effects of insect pests, and (iv) the effects of crop residues on insect pests’ population dynamics. Four major cropping systems namely: maize sole cropping without rotations by government sponsored farmers (GCP) (94 percent), maize intercropping without rotations by independent farmers (IF) (79 percent), maize sole cropping without rotations by IF (67 percent) and maize intercropping without rotations by GCP (61 percent) were identified. The choice of a cropping system by the smallholder farmers was significantly influenced by source of sponsorship, the difference in their district localities, tenure system, availability of inputs and farming equipment, percentage of farmland farmers allocate to maize, maize varieties, farming experience, fallow operations and access to irrigation facilities. The major constraints faced by the farmers in maize production are the attack by insect pests, weeds competition, drought, the lack of fencing around the fields and destruction by mammals. The major insect pests identified were stalk borers (Busseola fusca, Chilo partellus), cutworms (Agrotis spp.), aphids (Rhopalosiphum maidis), bollworms (Helicoverpa armigera) and weevils (Sitophylus spp.). The most popular control measures employed were the use of GM maize and pesticides. Results from the field trial showed that field crickets were the major ground dwelling insect pests observed followed by bollworms and cutworms. However, there were no significant influence of residue retention on the insects’ diversity indices, richness, and evenness. Above ground insects sampling revealed the domination by four major insects namely, cutworms, maize stalk borer, bollworms, and spotted stalk borer. Residue management significantly influenced the infestation by spotted stalk borer only on maize plots. However, the general trend was that there was less infestation by the insects in plots where residues were retained than the ones with residue removed. Results from the study indicate that government sponsorship is significantly influencing the maize cropping systems of the smallholder farmers of the Eastern Cape.

The leaching of nitrogen (N) and phosphorus (P) from the rootzone of cropping systems is a major contributor of non-point source pollution resulting in deterioration of fresh water supplies. An escalating world population is forcing further intensification of agricultural production practices and the identification of suitable and effective management practices to reduce N and P leaching losses is becoming ever more important. Such leaching losses are, however, extremely challenging to measure and quantify due to uncertainties associated with the estimation of deep drainage and N and P concentrations in this drainage water. SWB-Sci is a locally developed, mechanistic crop model to which N and P subroutines have been added to enable analysis of leaching losses at the local scale. This involved novel approaches to estimate the effects of N deficiencies on yield; to simulate crop P demand, uptake and stress effects; to simulate banded P fertilizer applications; and to estimate incomplete solute mixing. New equations to estimate the size of the Labile P pool from soil P tests commonly used in South Africa, and guidelines on the classification of South African soils as calcareous, slightly weathered or highly weathered which is required to simulate P, were also developed. The upgraded more versatile model was tested using historical datasets from the Netherlands, Kenya and South Africa, and performed well in simulating N and P dynamics in maize and wheat cropping systems. Variables tested included aboveground dry matter production, yield, leaf area index, aboveground crop N and P mass, grain N and P mass, soil water content ABSTRACT xvii and soil inorganic N levels. A study was also conducted on a large drainage lysimeter into which suction cups and wetting front detectors were installed, and data from this experiment together with the SWB-Sci model was used to study vertical solute movement more closely. As hypothesized, wetting front detector nitrate (NO3-) and P concentrations were observed to align closely with simulated mobile phase concentrations, and suction cup NO3- concentrations were observed to align closely with simulated immobile phase concentrations. These results confirm that monitoring and modelling can be used together to improve understanding and obtain more accurate estimates of N and P leaching losses, and further work on this approach is recommended for a wide range of soils and cropping systems. Finally, long-term modelling with the SWB-Sci model was used to analyse and compare N and P leaching losses from a dryland versus an irrigated monoculture maize production system. Over a 30 year simulation period, irrigated maize was estimated to leach considerably higher loads of N and P (~ 4-fold higher). For dryland production, zero leaching was observed for consecutive years on several occasions, with major leaching losses associated with high rainfall events. A ‘room for rain’ irrigation scheduling management practice was estimated to reduce N leaching by 12% and P leaching by 14%, while a crop rotation system which incorporated wheat grown over the winter months was estimated to reduce N leaching by 23% and P leaching by 24%. From this study, long-term modelling was confirmed as an effective approach to investigate N and P leaching losses, to assist with the planning and design of field trials, and to assess the effectiveness of best management practices. It is envisaged that SWB-Sci will continue to evolve as a valuable tool for analysing and reducing N and P leaching losses from cropping systems to further reduce non-point source pollution. / Thesis (PhD)--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

A major challenge facing agriculture today is to sustain the productivity of agricultural systems with the reduction of weed invasion. The Swartland region in the Western Cape (South Africa) is intensively cropped, producing wheat (Triticum aestivum) as the major crop. As a result of the weedy ryegrass invasion the wheat yield is reduced. In addition, ryegrass has developed resistance to grass herbicides (graminicides). This situation has increased the need to use alternative practices for controlling the invasion of ryegrass in wheat fields. In this regard, crop rotation and tillage systems were proposed as techniques to suppress the ryegrass invasion. This could thus maintain a sustainable long-term wheat production system with less application of herbicides, decreased input costs and increased total grain yield. Against this background, the effects of crop rotation and tillage were determined on ryegrass seedling emergence in a field and shade netting experiment, while seed dormancy was determined in the laboratory. The objectives were to compare the wheat production of two crop rotations with mono-cropped wheat and assess the impact on the ryegrass population in no-till and minimum tillage systems. Analyses of variance on data sets of ryegrass seeds from 2009, 2010 and 2011 were used to determine germination and dormancy percentages in laboratory experiments. The performance of laboratory treatments was evaluated on the basis of germination percentage of seeds. In the field and shade netting experiments, analyses of variance for data from 2007, 2011 and 2012 were used to determine crop rotation x tillage system response. Field and shade netting performance were evaluated on the basis of ryegrass population inhibition and stimulation respectively. Ryegrass seeds from 2009 and 2010 showed higher germination percentages (80 per cent and 73 per cent) than 2011 (42 per cent). Primary dormancy prevented high germination of newly harvested seeds as dormancy release increase with age of the seed. Results of field and shade netting experiments showed stimulation of the ryegrass weed population in wheat monoculture under minimum tillage. However, when wheat was rotated with leguminous crops under both tillage systems (minimum-till and no-till) ryegrass was significantly inhibited. It was concluded that the critical period for weed competition is the first six weeks after planting. Results from this study provide a basis for producers of cereals to make good decisions with regards to timing weed control measures. It is essential to use competitive crop sequences which will inhibit weeds. The challenge is getting this practice adopted and implemented by producers as it will promote conservation agriculture within the region. This study promotes long-term sustainable wheat production systems with an efficient weed management programme that is environmentally friendly using less herbicides within the Swartland region.

Maize is the most important cereal crop grown in areas of South Africa by both small-scale and commercial farmers. Maize monocropping without sufficient input and declining soil nitrogen content are some of the factors that limit yield. The objective of the study was to evaluate the effect of different cowpea cultivars and populations on growth, yield and yield components of succeeding maize. The effects of cropping systems on soil N content were also observed. Field experiments were conducted during the 2005/2006 and 2006/2007 growing seasons at Potchefstroom and Taung in North West province. The trial consisted of four cowpea cultivars: PAN 311 (short duration cowpea cultivar), CH 84, Bechuana white (medium duration cowpea cultivar) and TVU 1124 (long duration cowpea cultivar) and, four planting densities (10 000, 15 000, 20 000 and 40 000 plants ha-1). Maize was used as sequential test crop to determine the residual effect of previous cowpea treatments. Cowpea grain yield increased as planting density increased at both localities. TVU 1124 gave highest grain yield of all cowpea cultivars at both localities. Total dry matter yield also increased with increasing planting density. After cowpea soil NO3- and NH4+ content increased with increasing density. Similarly, soil NO3- content of maize following cowpea showed a considerable improvement, compared to maize monocropping. The highest soil NO3- and NH4+ content was observed when maize followed Bechuana White. Significant differences were also observed in soil microbial activities among the cultivars. Maize grain yields and plant height responded positively to the previous cowpea crop, compared with maize monocropping at both locations, but especially at Taung. Maize stover yield, cob length and KNC significantly responded to maize and cowpea rotation compared to maize monocropping at Taung. These results further confirm the potential of using cowpea to contribute soil N to subsequent maize crops in a rotational system. Copyright / Dissertation (MScAgric)--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

Inom arbetslivet finns situationer i vilka vi kan utnyttja digitalisering för att förenkla och effektivisera arbetet. Ett exempel är den analoga hanteringen av fysiska formulär. Oftast överförs data från fysiska formulär till datorn manuellt. Syftet med detta projekt är att effektivisera den generella hanteringen av pappersformulär genom inskanning. Detta kan göras genom att utnyttja en beskärningsfunktion vid inskanningen. Beskärningen används för att beskära bort irrelevant data från formuläret och därmed framhävs det som ska skannas in. Därefter kan objektigenkänning användas för att känna igen siffror och text från det framhävda fältet. En Androidapplikation har utvecklats som utnyttjar mobilens inbyggda kamera för att skanna in och framhäva viktiga fält från formulär. Parallellt tränades en maskininlärningsmodell, med TensorFlow, att känna igen handskrivna siffror. Den färdigtränade modellen jämfördes med olika OCR-verktyg och resultatet visade att modellen detekterar handskrivna siffror bättre. / A workplace can be made more efficient by digitalization. An example of that is the handling of forms. Most of the time physical forms are manually digitalized. The aim of this project is to simplify the general handling of forms by automating the process. This could be done by scanning photos of forms and using a cropping function to highlight the important parts. By doing this we can use object detection to recognize the text or numbers on that highlighted field. An application was built that utilizes a phone camera to snap a photo of a form, and then a cropping function was implemented to crop out the important part of the form excluding irrelevant data. Parallel to that a machine learning model was trained with TensorFlow to recognize handwritten numbers to work with the application. The trained model was evaluated and compared to different OCR tools, and the results showed that a model trained to detect a specific handwriting works better than general OCR tools on handwritten digits.

This thesis investigates the relationship between groundnut cash cropping decisions and household food security in two regions of sub-Saharan Africa.  Particular attention is paid to how the gender of groundnut growers influences this relationship.  Additionally, the thesis examines how gender influences household marketing decisions.  Household groundnut production and marketing data was obtained using surveys administered in eastern Uganda and central Ghana.  A food consumption score developed by the World Food Program is used as a quantitative measure of food security.  Measures of household groundnut cultivation intensity are specified using data on household groundnut production and marketing levels.  An OLS regression estimates the relationship between the food consumption score and measures of cash cropping intensity and other cash crop production decisions.  Apart from the OLS regression, a tobit model is employed to estimate the gender effects on household marketing decisions, examining both the decision to participate in a market and the decision concerning the amount to market.  Cash cropping decisions are found to play no role in the determination of food security.  While the presence of female groundnut growers in a household has a small positive effect on the food consumption score, there is no identifiable gender influence upon the cash cropping and food security relationship.  The tobit model results indicate no gender effect upon household marketing decisions. / Master of Science