Collecting additional data to calibrate and refine current guidelines for interpreting soil and plant test values is an ongoing need in Arizona. An experiment was conducted at the Safford Agricultural Center during the 1987 -89 crop years to evaluate the response of 'Aldura' durum wheat to a range of residual soil and fertilizer P levels. Maximum grain yields exceeding 5,500 lbs./A were obtained by banding 50 lbs. P₂O₅/A as triple superphosphate with the seed at planting in 1988. Residual P front phosphorus fertilizer applications up to 80 lbs. P₂O₅/A had no significant effect on grain yields of the succeeding wheat crop. Basal stem PO₄-P tissue analysis seemed reliable in monitoring P nutrition of durum wheat during the vegetative growth period. Observed critical levels of POD P in basal stem tissue for durum wheat at the 3-4 leaf, joint and boot growth stages were 2000, 1200 and 500 ppm, respectively.

A field experiment was conducted on a Pima clay loam at the Safford Agricultural Center to: 1) determine the optimum rates of late season N needed to achieve optimum yield and quality of irrigated durum wheat in conjunction with varying rates of early season N; and 2) evaluate the usefulness of stern NO₃-N analysis in predicting the late season N rates which optimize grain production but minimize the potential for nitrate pollution of groundwater. The application of 75, 175 and 350 lbs. N/a during vegetative growth resulted in wheat with deficient, sufficient and excessive N status at the boot stage, as indicated by stem NO₃-N analysis. The application of 60 lbs. N/a at heading to N- deficient wheat and 15-20 lbs. N/a to N-sufficient wheat resulted in grain protein levels above 14 %, but the applications had little effecton grain yield. Applications of N at heading to wheat which had previously received excessive N did not affect grain yield or quality. The use of stein NO₃-N analysis appears to be a useful tool in predicting the minimum N rate to be applied during the early reproductive period to insure acceptable levels of grain protein at harvest.

Wheat irrigations were scheduled using two computer models and an infrared thermometer, using three critical threshold values. Yields from these plots were compared with plots scheduled by the farm manager. The highest yield was obtained by the computer model using evapotranspiration data taken from the local AZMET station; this corroborates results from the previous year. The crop coefficients and the irrigation model that have been developed over the past several years are very accurate for this area. The two lower threshold infrared treatments were second and third in yield and had lower water use efficiencies.

La pollution diffuse provenant des milieux agricoles a une influence majeure sur la qualité de l’eau. Le transport de sédiments et de nutriments, tels que le phosphore et l’azote, est particulièrement préoccupant. Les changements climatiques anticipés modifieront le régime hydrologique des rivières, ce qui entraînera des conséquences difficiles à anticiper, notamment sur la qualité de l’eau. Le site à l’étude est le bassin versant de la rivière Tomifobia, situé au sud-ouest du Québec, qui possède une superficie de 436 km² et qui comporte une forte activité agricole. Il a un impact important sur la qualité de l’eau du lac Massawippi puisqu’il draine 70% de son bassin versant. Le modèle hydrologique spatialisé Soil and Water Assessment Tool (SWAT) a été utilisé pour effectuer l’évaluation quantitative et qualitative de l’apport en eau à la rivière. Les activités agricoles ont été représentées dans le modèle selon un calendrier typique pour chacune des différentes cultures. Le calage et la validation du modèle pour le débit de la rivière Tomifobia ont été effectués à l’aide de la reconstitution des apports au lac Massawippi. Pour la qualité de l’eau, les données provenant de l’Institut de recherche et de développement en agroenvironnement (IRDA), du Comité de gestion du bassin versant de la rivière Saint-François (COGESAF) et la campagne d’échantillonnage du Groupe de recherche sur l’eau de l’Université de Sherbrooke (GREAUS) ont été utilisées. Les éléments analysés par rapport à la qualité de l’eau sont les sédiments, le phosphore et les nitrates. Différentes projections climatiques ont été entrées dans le modèle dans le but de déterminer les tendances hydrologiques futures. L’impact des changements climatiques sur le régime hydrologique se traduit principalement par une augmentation des débits hivernaux et une diminution des débits printaniers. Aucune tendance statistiquement significative n’a été observée pour la période estivale et automnale. L’effet des changements climatiques sur les exportations de nitrates est similaire à celui sur le débit. Pour les exportations de sédiments et de phosphore, on note une hausse à l’hiver, une baisse au printemps et une hausse pour l’été et l’automne.

The increasing demand worldwide for Australian wine has driven the recent expansion in vineyard plantings which in turn, has increased the requirement for irrigation water in grape growing regions. Large areas of Australia's national vineyard are already irrigated with relatively poor quality water and many districts have a limited supply of water available for irrigation. Therefore, improving the efficiency of vineyard irrigation is essential for the long term sustainability of the Australian wine industry. Reducing the volume of irrigation applied to vineyards can improve water use efficiency (WUE) and reduce vine vigour. However, it can be difficult to accurately apply the required degree of water stress and this may result in a yield reduction. An irrigation technique known as partial rootzone drying (PRD) involves applying a continuous water deficit to alternate sides of the root system while ensuring the other half is well watered. This has been found to increase WUE, reduce vine vigour, improve fruit quality but not affect vine yield. Where the soil volume available for root growth is limited, so too is the resultant vine growth and yield, as access to water and nutrients is restricted. Shallow soil profiles present a major limitation to root development and grapevine vigour. In shallow soils, mounding topsoil from the vineyard mid row to form raised beds in the vine row has been found to improve vine growth and productivity. Soil mounds tend to have a higher moisture holding capacity than flat soil but the greater surface area of the mound can increase surface evaporation. Applying mulch to the mound surface has been shown to reduce evaporative soil moisture loss and conserve irrigation water. The general hypothesis tested in this experiment was that: 'Combining soil mounding, straw mulch and partial rootzone drying (PRD) irrigation will improve grapevine growth and production and reduce levels of sodium and chloride in the vine.' The experiment was established on Vitis vinifera cv. Shiraz in a mature vineyard at Padthaway, South Australia, where the soil profile consisted of a shallow loam over clay and limestone. Soils of the experimental site were classified as moderately saline because their electrical conductivity (ECse) was greater than 4 dS/m. Three main factors, irrigation method (standard or PRD), soil mounding (flat or mounded) and surface cover (bare or straw mulch) were combined into a 2X2X2 factorial experiment such that the randomised block experiment comprised three replicates of eight treatments. The irrigation treatments were control (the application of water to both sides of the vines) and PRD (the application of water to one side of the vines only at any time). In the PRD treatment the frequency of alternating the 'wet' and 'dry' sides was determined according to soil moisture measurements and was typically every 5-7 days. It was very difficult to accurately schedule the irrigation at this site to avoid applying a moisture deficit to the PRD treatment. The shallow soil profile dried very quickly following irrigation and there were problems with the accuracy of the soil moisture sensing equipment for the duration of the experiment. As a result, PRD vines experienced repeated, excessive soil moisture deficits such that vine growth and production were significantly reduced each season. Shoot length was measured weekly during the growing season, while photosynthetically- active radiation (PAR), leaf area and canopy volume were measured at full canopy. Shoot number and pruning weight were measured during dormancy. All measures of vegetative growth (with the exception of PAR) were reduced in response to PRD. The decrease in lateral shoot growth for PRD resulted in greater bunch exposure and PAR. As a direct result of the severe soil moisture deficits experienced by the PRD treatment, all components of yield were significantly reduced compared to the control treatment each season. In particular, bunch weight and berry weight were significantly lower in the PRD treatment compared to the control, which suggests a period(s) of severe soil moisture deficit was experienced. Despite the yield loss sustained by the PRD treatment, WUE was improved compared to the control treatment in the first two years of this experiment. Berry anthocyanin levels were higher for the PRD treatment than the control but this may be due to the reduction in berry size. Weekly volumetric soil moisture monitoring showed that mounded soil was wetter than flat soil each year at similar horizons. In addition, the larger soil volume of the mounded treatment enhanced vine root development. Vegetative growth was greater in the mounded treatment than the flat treatment. Mounded vines grew more shoots than non-mounded vines, although there was no effect of mounding treatment on shoot length. The difference in shoot number was significant only in year 2, possibly due to the time required for vine roots to establish in the mounds. Pruning weight and mean shoot weight were higher for the mounded treatment each year and mounded vines grew more shoots than non-mounded vines in years 1 and 2. The increase in shoot weight of mounded vines, relative to non-mounded, was most likely due to the increase in lateral shoot growth which is supported by the lower PAR values of the mounded treatment compared to the flat treatment. Each year soil mounding resulted in higher vine yields than in flat soil beds as a direct result of the increased vine capacity of mounded vines. The mounded treatment had more shoots per vine than the non-mounded treatment and thus more bunches per vine. In addition, bunch weights were higher in the mounded treatment each year, due mainly to improved fruit set and more berries per bunch. Despite the mounded treatment resulting in a denser canopy than the non-mounded treatment this did not affect fruit composition in years 1 and 2. WUE was higher for the mound treatment in years 2 and 3 only, due to the volume of irrigation water applied being reduced, yet mounded vines continued to produce higher yields than non-mounded vines. In year 3, berries from vines grown in mounded soil had significantly higher pH than berries from vines grown in flat soil beds. Mounding treatment did not consistently affect berry anthocyanin or phenolic levels. Soil moisture levels were higher in the mulch treatment than the bare treatment in all seasons. In contrast to the mounding treatment, wetter soil did not consistently lead to improved vine growth or yield. Mulched vines developed fewer roots than non-mulched vines which is likely to have limited vine access to water and nutrients. As a result, shoot growth was similar for both treatments each season. The only significant difference between treatments for pruning weight was found in year 3 and was due entirely to shoot weight. The mulched treatment had lower PAR than the bare treatment in year 3, probably the result of increased lateral shoot growth and thus increased shoot weight, although this was not significant. PAR was significantly higher for the mulch treatment, compared to the bare treatment, in year 1 only but this was not supported by significant increases in vegetative growth. The mulch treatment resulted in higher vine yield than the non-mulch treatment in years 1 and 3. This difference was significant in year 3 only when both bunch number and bunch weight were significantly higher for mulched vines. In year 1 only bunch weight was significantly higher for mulched vines. Differences between treatments occurred in year 2 for fruit composition, specifically juice TA and anthocyanin levels. The mulch treatment had significantly higher TA and a significantly lower anthocyanin concentration in berries than the non-mulch treatment in year 2. There was no evidence of increased shading in the mulched treatment relative to the bare treatment that year but the difference in anthocyanin concentration may be explained by the significantly smaller berries of the bare treatment. Analysis of samples taken regularly from the soil profile and vine rootzone showed that there was no treatment effect on soil salinity but that soil ECse increased with soil depth and time each year. Petiole samples were collected at flowering, veraison and pre-harvest and levels were deemed toxic by pre-harvest each year. The PRD treatment received approximately 60% of the salt applied to the control treatment. This did not reduce ECse but did result in lower measures of sodium and chloride in petioles and juice at harvest. Vines grown in soil mounds had access to a greater volume of soil water than the non-mounded vines. The mounded treatment had higher levels of pre-harvest petiole chloride in years 1 and 3 but this was significant only in year 3. There was no consistent trend in levels of sodium and chloride in the juice from either mound treatment, although in year 3 berry extract chloride levels were found to be significantly higher in the mounded treatment than the flat treatment. Similarly, a consistent trend in sodium and chloride levels of petioles and juice was not evident for the mulch treatment. Although, in year 3 petioles of vines grown in bare soil were found to contain significantly more petiole chloride than those which had straw mulch applied. The hypothesis that combining soil mounding, straw mulch and partial rootzone drying (PRD) irrigation will improve grapevine growth and production and reduce levels of sodium and chloride in the vine is rejected as there was not a consistent, cumulative effect of the three factors in this experiment. / Thesis (M.Ag.Sc.)--School of Agriculture and Wine, 2005.

In the Philippines, about 38 per cent of the total population resides in rural areas where poverty remains a significant problem, especially in remote upland communities. Soil erosion has been a well-recognised problem in these areas, resulting in a number of impacts on the livelihoods of the rural poor. The development and dissemination of soil and water resource conservation (SWC) techniques has been seen as essential to achieving improved and lasting outcomes for the livelihoods of upland communities, with benefits spilling over beyond the farm boundary. The participatory development of a cost-effective means of controlling soil erosion, natural vegetative strips (NVS), has increased the adoptability of SWC for many upland households, enabling them to incorporate agroforestry and other practices in their farming systems. The Landcare Program in the southern Philippines has facilitated the adoption of these practices over the past decade. However, the impacts of adoption on the livelihoods of farming households, and the externalities that adoption may deliver, have remained speculative. This thesis first explores whether the adoption of Landcare practices has resulted in improved livelihood outcomes for upland farming families. Second, it analyses the potential for the piecemeal adoption of these measures to deliver tangible benefits at the watershed scale. Finally, using a benefit-cost approach, these outcomes are compared to the costs of the research and extension projects that have helped achieve them. The analysis is carried out in two upland municipalities, San Isidro and Pilar, in the Province of Bohol. Landcare households in Bohol dedicate a large percentage of household resources to the production of rainfed rice, which is the primary source of subsistence for adopting households while upland plots play a secondary role. The adoption of NVS alone did not typically generate significant economic benefits, yet created the stable platform on which more commercial investments were being made, especially through NVS enrichment. In San Isidro, the average annual income of adopters generated from upland activities was estimated to be more than double that of non-adopters, with a difference of over PHP 7,500. In Pilar, the net impacts of adoption were estimated to be only around PHP 3,700, given that many households had not enriched their NVS at the time of the survey. At the household level, the benefits of adoption are therefore contingent on the ability of the household to make further investments in their farming system, stemming from improved soil stability. Several case studies were used to describe the process of and constraints to farm development. The average impacts on incomes were found to be significant at the household level, with the potential to lift a household above the poverty threshold. Yet the marginal nature of the upland farming systems limits the aggregate on-site benefits. The expansion of activities into Pilar and Alicia was estimated to increase the net annual benefits, reaching PHP 2,270,000 (around AUD 60,000) per year by 2009. In absolute terms, this impact is still quite modest, but needs to be considered together with the off-site impacts and the costs of the Landcare Program. In Pilar, one of the clearest impacts of erosion due (in part) to upland cropping has been the sedimentation of the Malinao Dam. The significance and distribution of forgone revenue from irrigated rice as a result of sedimentation is largely determined by factors including the timing of rainfall events, the allocation of water between users, and the value of alternative land uses. Furthermore, the upland agricultural landscapes of Bohol are diverse and complex, with numerous sources and filters of sediment. A terrain analysis model was used to model the impact of incremental adoption of Landcare practices within the landscape. The results show that the spatial distribution of adoption is likely to be as important as the extent of adoption when it comes to delivering off-site benefits. The aggregate level of losses avoided as a result of Landcare was estimated to be around PHP 1,023,000 (AUD 26,900) over a 20-year period at a discount rate of five per cent. The results of the livelihood analysis and watershed modelling were combined in a benefit-cost analysis (BCA) and compared to the costs of the projects and other investments that have helped bring about the impacts. The results showed a positive but small NPV of around PHP 3.5 million, equating to around AUD 91,000, for the 20 year period simulated, using a 5 per cent discount rate. The sunk costs of the early phases of theLandcare Program, however, continue to provide the basis for ongoing livelihood projects that utilise farmer groups as a means of extension. Furthermore, when the expansion of the Program into other nearby municipalities can draw on the original research or learning hub, rapid adoption can be achieved at relatively low cost and provide a significant return on investment. Overall, the evidence presented indicates that the net economic impacts of the Landcare Program in Bohol are positive, even when taking into account the prior investment in research and training. The major beneficiaries of the Program are the individual households who adopt the conservation farming practices, with these benefits largely generated by the farming opportunities stemming from improved soil stability. The diversification and commercialisation of the upland component of the farming system has mainly utilised land and labour at low opportunity cost, though limited access to these resources prevents some households from proceeding along the identified farm development pathway. The focus on livelihood development does not deny the seriousness of downstream watershed problems arising from upland agriculture. However, it is agued that given the relativity of on-site and off-site benefits, the focus and primary justification of the Landcare Program should remain on improving the productivity and livelihoods of upland farmers through facilitated, farmer-led, group-based research and extension, with these downstream impacts being seen as side benefits of what is essentially a livelihoods program.

ABSTRACT SOIL AND WATER ANALYSIS TECHNIQUES FOR AGRICULTURAL PRODUCTION Maral, Nuh M. Sc., Department of Chemistry Supervisor: Prof. Dr. G. inci G&ouml / kmen May 2010, 108 pages In Turkey, usage of increasing amounts of fertilizers and pesticides by some unconscious farmers cause soil pollution and soil infertility for the crop production. Usage of water in excessive amounts and/or in poor quality for irrigation creates problems during the plant production. So in this study, soil and water samples were analyzed by using simple and reliable techniques for the soil and water quality in laboratories of METU and Soil Fertilizer and Water Resources Central Research Institute Laboratory in Ankara. The soil and water samples were collected using the standard techniques from Ankara, Bolu, &Ccedil / orum and Kirikkale. According to the soil test results, the textures of the soil samples are found as loam and clay loam. The total salt content of the soil samples are between 0.033 &ndash / 0.063 % (w/w), meaning they are low salinity soils (total salt less than 0.15 % w/w). The pH of the soil samples are between 7.86&ndash / 8.15, they are slightly alkaline. The phosphorus concentrations of soil samples are in a range 4.95 to 35.45 P2O5 kg/da. Some of the soil samples have too high phosphorus content (greater than 12 P2O5 kg/da). The potassium content of soil samples are found between 141&ndash / 286 K2O kg/da, so the soil is efficient for crop production. Lime content of the soil samples is between 1.04&ndash / 2.67 % (w/w) CaCO3. It means all of the soil samples are calcareous but it is not too high for the agricultural production. Organic matter content of soil samples are found between 0.83&ndash / 2.04 % (w/w). This means the soils are limited in their organic matter content for the crop production. Analysis of 22 water samples yielded EC values between 0.384 &ndash / 1.875 dS/m. Water samples have moderate to high-salinity (if EC values between 0.205 and 2.250 dS/m), yet these can be used for the irrigation of the crops. pH values of water samples are found between 7.18-8.10, meaning that they are slightly alkaline. Bicarbonate concentrations of 19 of the water samples are greater than 200 mg/L. These waters may not be suitable for irrigation of ornamental plants. All of the water samples, except water samples from G&ouml / lbaSi, have sodium absorption ratio (SAR) values between 1 and 9. Water samples with low SAR values, except water samples from G&ouml / lbaSi, can be used for irrigation of almost all soils with little danger of developing harmful levels of sodium. The Residual Sodium Carbonate (RSC) values of water samples Ankara G&ouml / lbaSi and Sincan-1 are greater than 2.50 meq/L and these water samples are not suitable for the irrigation. RSC values of Etimesgut, Sincan-2 and Kazan water samples are positive and lower than the value 2.00 meq /L. All the other water samples have negative RSC values so they are the safe to use for irrigation. It has been observed that development of practical field analysis techniques for all soil and water quality parameters may be possible with exception of micronutrient determination. For determining soil and water quality parameters in the rural areas there is a need to establish a small laboratory with necessary equipment and apparatus and training one or two farmers. With the experience gained in this study, some of these techniques may be adapted to the rural field applications, so soil and water may be tested by the farmers for better yields.

Residential on-site wastewater systems (OWS) are a potential source of phosphorus (P) which can negatively impact surface water quality in rural watersheds. The magnitude of P loading from OWS is typically not monitored, and is further complicated when agricultural land-uses are intermixed with residential dwellings. Watershed-scale computer simulations are commonly used tools for evaluating the impacts of land-use changes on P loading. Existing models simulate OWS P treatment via vertical flow transport in native soils. However, in Nova Scotia (NS) OWS designs rely pre-dominantly on lateral flow and imported sand filter media. In this thesis, a watershed-scale computer modeling framework for simulating P loads from agriculture and lateral flow OWS designs was developed and tested. The framework consists of the P on-site wastewater simulator (POWSIM), designed specifically for this study, which is used in conjunction with the Soil and Water Assessment Tool (SWAT) model. The POWSIM loading tool has three computational components: (i) OWS disposal field design type selection and treatment media mass calculation; (ii) disposal field P treatment dynamics; and (iii) soil subsurface plume P treatment dynamics. The active P treatment media mass and dynamics equations were developed from numerical modeling (HYDRUS-2D) and lateral flow sand filter (LFSF) OWS disposal field experiments. A 2-part piecewise linear model was found to best represent LFSF P treatment processes. Testing of the modeling framework in the mixed land-use Thomas Brook Watershed (TBW) in NS demonstrated improved simulation of baseflow total P (TP) loads in both a predominantly residential subcatchment and one dominated by agriculture over the SWAT model without POWSIM. Different residential and agricultural development and beneficial management practice (BMP) scenarios were evaluated in the TBW. Agricultural BMPs were most effective at reducing cumulative TP loads while OWS BMPs were best at mitigating in-stream eutrophication impacts. The 50 year simulation period for the various scenarios found peak OWS TP loading occurring between 25 and 50 years, suggesting that modeling for many decades is required for proper evaluation. This study highlights the importance in identifying specific water quality issues that need to be targeted prior to implementing a BMP strategy.

This dissertation focuses on the economic and environmental benefits of planting switchgrass as a bioenergy feedstock. The first chapter presents a dynamic optimization model of fertilizer and land allocation between switchgrass and corn to estimate economic benefits. Subsequent chapters utilize Geographic Information System (GIS)-based Soil and Water Assessment Tool (SWAT) to be calibrated to evaluate the environmental (nutrient and sediment loading) effects of land use conversion to switchgrass production on water quality and analyze the Water Quality Trading (WQT) program with cost-effectiveness ratios ordered for abatements of nutrient loadings in an East Tennessee watershed.

The potential of proximal soil sensing methods for high resolution investigation of soils in the landscape has been investigated. This addresses the need for improved environmental monitoring and management of soils within their environs. On-the-go electromagnetic (EM) mapping has been used to map soils, providing a high resolution (< 10m) spatially defined soil apparent electrical conductivity (ECa) datalayer. Vis-NIR field spectroscopy has been trialled for in situ analysis of soil carbon, nitrogen and moisture. The portable spectroradiometer has been used at 6 sites in the Taupo-Rotorua region for rapid, field analysis of soil carbon (R2 calibration = 0.95, R2 prediction = 0.75,) soil nitrogen (R2 calibration = 0.95, R2 prediction = 0.86) and moisture (R2 calibration = 0.96, R2 prediction = 0.70) by collecting reflectance spectra from the flat surface of a soil core; and at one Manawatu site for soil moisture (R2 calibration = 0.79, R2 prediction = 0.71), where the reflectance spectra were collected directly from a freshly cut in situ soil surface. EM mapping and Vis-NIR field spectroscopy were used in combination to spatially characterize soil moisture patterns at the Manawatu site. Soil available water-holding capacity (AWC) of ECa-defined zones has been assessed at six irrigated production farming sites. Two methods (predicted AWC v ECa; estimated AWC v ECa) have been used to relate soil ECa to soil AWC to predict spatial AWC (R2 = 0.8 at 5 sites). Site-specific soil water balance models have been developed at all sites; and a wireless real-time soil moisture monitoring network has been trialled at two sites, to be used with the ECa-AWC prediction model for the development of daily soil water status maps, for variable rate irrigation (VRI) scheduling. This digital, spatially defined soil water status information is available for upload to a sprinkler system modified for variable rate application. The calculated water savings with VRI were 926% with equivalent energy savings and improved irrigation water use efficiency. Drainage and runoff were reduced by 055% during the period of irrigation, with the accompanying reduced risk of nitrogen leaching. The reduction in virtual water content of product has also been assessed for VRI and compared with uniform rate irrigation (URI) at three study sites. This study suggests that these proximal sensing methods provide a new improved way of monitoring and mapping soils. This facilitates soil inventory mapping, for example soil moisture and carbon mapping. In addition, these high resolution environmental monitoring and mapping techniques provide the information required for optimizing site-specific management of natural resources at the farm scale. On-the-go electromagnetic (EM) mapping has enabled a step change in the pedological investigation of New Zealand soils. Resulting soil ECa maps provide a tool for improving traditional soil map boundaries because they delineate soil zones primarily on a basis of soil texture and moisture in non-saline soils. In this study the maps have been used for site-specific irrigation management at the farm-scale, aiming to increase the energy efficiency of this land management operation. The study has developed a method for improved use of freshwaters by more accurate irrigation scheduling, based on high resolution characterization of spatial and temporal soil differences.