This study occurred at the Ventilla Ecologic farm, situated in the central Altiplano of the Murillo province, 26 km from La Paz. Its objectives were to evaluate two types of irrigation, by drip and by microasperation, in spinach and Swiss lettuce in Walipinis, and to conduct an economic analysis. The genetic material used was spinach (viroflay variety) and Swiss lettuce (large-leaved variety). Chapin irrigation belts and nebulizers were used, and two tensiometers were used to determine the soil moisture. Manual planting occurred on September 1, 2002, in all experimental areas. Seeds were dispersed in a continual flow with Swiss lettuce at a density of 3.5g/m2 and three bobbins, and in spinach the density was 0.26 g/m2 in parallel, 20 cm rows with the irrigation belts on either side. The spinach harvest was spread out, while the Swiss lettuce harvest occurred all at once. A factorial arrangement was used in this study, with two factors: two levels of irrigation (drip and microasperation) and different crops (spinach and Swiss lettuce). The response variables regarding drip irrigation efficiency had a uniformity coefficient of 97%, and microasperation had 85%. The depth reached by the watered bulb after two hours of control was more than 20 cm, while the microasperation only reached 15 cm after two hours. Irrigation occurred at midday but in accordance with the readings that the tensiometers gave. The response variables studied in the crop were: percentage germination, number of leaves, plant size, leaf size, and yield. Yield showed significant differences between types of irrigation of crops. Drip irrigation was better than microasperation. The response variables that had the greatest effect on yield were number of leaves, plant size, and leaf size. The economic production analysis found negative net benefits for the first trial. In the second trial, drip irrigation netted Bs.3.54/m2 for spinach and Bs. 3.68/m2 for Swiss lettuce, recovering the investment from the first trial. In contrast, the yield from microasperation irrigation, even though the second trial had positive net results, did not recover the investment from the first trial. Finally, based on these data, drip irrigation is recommended because of its better yields and a lower installation cost.

Most families in the area of Tiahuanaco, Bolivia participate in livestock production, mainly cattle breeding. The primary feed sources for livestock in this area are native grasses, barley, and, to a smaller degree, oats. These grasses have low yield because of climate and soil conditions. This area does not have enough forage, especially during the dry season, and the animals are not regularly fed during the year. Consequently, animal production is low. This research was conducted during 2001 and 2002 at the Bolivian Catholic University campus, Farmer’s Academic Unit of Tiahuanaco, Ingavi Province, La Paz, Bolivia. Study site locations were characterized by clay soils, low fertility, an annual median temperature of 8.35° C, and a mean precipitation of 495.4 mm. Five species of grasses were used: Agropyron trichophorum Link (Pubescent), Dactylis glomerata L. (Dactilo-Orchard), Agropyron cristatum Gaertn (Agropiro), Phleum pratensis L. (Fleo), and Bromus inermis Leysser (Bromo). In order to evaluate agronomic behavior of the forage grasses, the following measurements were collected: plant height, population size, leaf width and length, number of sprouts per plant, soil hedging, and yields of green and dry matter.

The present work was conducted in order to determine an adequate variety in the processing of small corn, in which a monitoring of all the cycle in cultivation was conducted. The behavior of the small corn was analyzed in the laboratory before the presence of three antioxidants, ascorbic acid, acetic acid and sodium sulfate in two concentrations in addition to subjecting them to thermal treatments that allows us to obtain a pleasant product for the consumer that is both resistant to treatment and nutritious for the health. The results indicate that the best variety of corn is muruchi yellow, the most effective antioxidant is sodium sulfate with a concentration of 1% and the thermal treatment of 10 minutes which obtained the best results, being most pleasing to those persons that evaluated the corn for its organic qualities followed by the ascorbic and acetic acid provided which provided a project of industrial feasibility that provides the information as a convenience to investment.

The present investigation was done in the parish of Chaltura, Granja "La Pradera" which belongs to the University Técnica del Norte. The main objective of this investigation was to determine the primary levels of the residues of the seeds of wheat, maize, barley for the elaboration of the food mixture for rabbits. The evaluated variables, food consumed, weight gain, food value, protein percentage, production cost per treatment. Previously to the initiation of the field phase bromatological analysis were done on the three food mixtures in the National Institute of Farming Investigation, Quality and Nutrition Area. The treatments were four: TI 13.84% of protein, T2 15.87% of protein, T3 19.57% of protein, T4 (Testigo) 18% of protein The field phase lasted 90 days and 48 rabbits of the New Zealand race were used, 50% males, 50% females each of 45 days old. A randomly design was used with four treatments and six repetitions, also in the different determined significant cases between the used treatments in the Tukey 5% test From the analysis obtained the results were to administer food with a low level of protein, animal consume a major quantity like we can observe in the results of the TI which has 13.84% of protein raising the production costs, while in the major treatment the T2, which has 15.87% of protein, because of its composition it was good tasting for the animals, making the consumption of the food will increase the normal weight, and the cost of production per Kg. Of food is $0.28. The T3 has 19.57% of protein the same which is in excess since the animals only assimilate what they need and the rest is the cost of production per Kg. Of food is $0.28. The T3 has 19.57% of protein the same which is in excess since the animals only assimilate what they need and the rest is waste, besides raising the protein level, this raises the cost of the food mixture. And the commercial food the T4 (Testigo) had reasonable results, in the food consumption of the pellet food mixture like the weight increase, but it is not recommended for farming families for the cost of Kg. $0.40, giving also another alternative like the T2(15.87% of protein) with a cost of Kg. Of $0.28. Besides the experimental mixtures to the animals water was supplied and 150 gr. Of alfalfa in the afternoon on a daily basis. An enabling study was done about the raising of rabbits, and the elaboration of the food mixtures in the various families of the Agualongo, Chimbaloma, Pucará, Peguche, Imbaya, Iluman, Compania, Agato, Calpaqui, Punyaro, Quinchuqui, communities, all belonging to Antonio Ante and Otavalo.

This study took place in Bolivia with the purpose of using thermally treated Capinota phosphate rock as a phosphorous supplement in balanced feed diets. The objective was to produce a natural phosphate substance that would be more easily accessible to the local population than commercial feed supplements. An additional objective of this study was to increase the availability of the low-fluoride phosphorous. The biological assays indicated that the diet with the added burned phosphoric rock produced similar yields to those using a commercial feed supplement (dicalcium phosphate). This indicates that the locally manufactured product, by partial acidification, can compete with similar commercial products.

Packaging Materials account for 31% of the world’s municipal solid waste. Agencies like the Environmental Protection Agency (EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR) are pushing for the increased use of recycled thermoplastic materials. Polyethylene terephthalate (PET) is a commonly recycled thermoplastic which is used to package ready-to-eat fruits and vegetables. Most recycled polyethylene terephthalate (RPET) packaging materials contain heavy metal catalysts, the most common being antimony. The recent increased use of recycled plastic materials has been suspected as the source of increased human heavy metal exposure. In this study, cadmium, chromium, nickel, lead and antimony were quantified in post-consumer RPET rigid containers and films using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Two hundred samples were tested of which 29 were found to be contaminated with heavy metals in the parts-per-million (ppm) range. Chromium was found in all the contaminated sample replicates at an average level of 8.18 ppm. Cadmium was found in all the contaminated samples as well. Lead was found in 90.4% of the contaminated samples and concentrations ranged from a low of 0.02 ppm to a high of 0.36 ppm. Nickel was found in 96.4% of the contaminated samples while antimony was found in 97.6% of the samples. Due to limited sample material, 22 of the 29 contaminated RPET rigid containers and films were tested for heavy metal migration into a 5% citric acid:water solution (w/v) or deionized water. Samples were subjected to prolonged storage at 7.2 or 22.2°C for 1, 7 or 14 days, or were exposed for 5 minutes to microwaves from a 1700-watt microwave oven set to 70% power before analysis. Leachate values were at ppb levels but were often below the ICP-AES Limits of Detection which were at also the ppb level, whether calculated for deionized water or 5% citric acid in water. No measureable levels of heavy metal were detected for any sample exposed to water, regardless of treatment. For samples exposed to 5% citrate and stored or microwaved, only chromium and nickel leached at measurable levels, and the number of RPET’s releasing measurable chromium and nickel increased with microwaving compared to the same plastics stored at 22.2 or 7.2°C. Since leaching was calculated as µg/L of heavy metal lost from the entire inner surface (1021 cm2) of a retail salad bag, actual exposure to heavy metal would be much less than measured in this study as retail fruit and vegetable packages and microwaveable pouches usually contain very little liquid in order to increase food safety. The results therefore suggest the potential for little migration of heavy metal from recycled PET to whole or fresh-cut fruits and vegetables when held at ambient or refrigerated temperatures, or when microwaved.

This project was designed to correlate environmental variables with the development of Pierce’s Disease (PD), an infection caused by the gram negative bacterium Xylella fastidiosa (Xf), in grapes (Hopkins et al. 2002). PD is one of the most difficult crop pathogens to manage because it is vectored by insects and its continued presence in the vine is usually fatal. PD is influenced by the interaction of host, disease and vector, and probably many other environmental variables. The general objective was to study and identify the most important variables involved in the expression of Pierce’s Disease. Over a two year period, from a total of eight sites in northern and southern California data was collected on forty-five environmental variables including those relating to soil moisture, soil chemistry, soil nutritional status, vine nutritional status, vine water status, in-season and dormant season climate, incidence of Xf in adjacent vineyard vegetation, sharpshooter species and abundance at each location, and proximity of vineyard field sites to citrus or riparian areas. The environmental variables were analyzed with canonical correspondence analysis (CCA) to determine significance of each as they correspond with increased disease severity. The significance of environmental variables produced by CCA indicates increased soil moisture as the leading cause for increased PD incidence; several other environmental variables positively correlate with increased disease presence. Conversely, vineyard factors identified by CCA as not conducive to disease formation may play an inhibitory role in PD severity. We undertook polymerase chain reaction (PCR) to test for the presence of PD in vegetative samples, using a 733 base pair probe specific to Xf. These samples indicate alternative hosts in adjacent locations which act as reservoirs of Pierce’s Disease as well as verifying diseased vines within the vineyard locations.

Effects of nitrogen management and cultivar on strawberry production under disease pressure Kamille Garcia-Brucher California strawberry growers face increasing regulatory pressures to manage nitrogen (N) applications in their production system. Standard practice in the California strawberry industry is to apply a synthetic pre-plant controlled release fertilizer (CRF) to ensure the crop has sufficient N during winter establishment. Some research from the UC Cooperative Extension suggests this practice is not efficient at delivering N to the crop since most of the N is released from CRF before strawberry crop N uptake is significant. Another concern for California strawberry growers is loss of their crop to a myriad of soilborne pathogens. Compost is commonly applied as a soil amendment in California strawberry fields as it offers both agronomic and environmental benefits including the potential for disease suppression. In light of legislation restricting N in some California cropping systems, Ag Order 4.0, and incentives programs established to promote soil conservation practices, compost may be a viable substitute for synthetic pre-plant CRF N. In this study, we investigated the effects of pre-plant fertilizer and strawberry cultivar on fruit yield, disease incidence, soil and plant N dynamics and soil carbon (C) at the Cal Poly Strawberry Center, San Luis Obispo, CA in a field infested with Macrophomina phaseolina. Pre-plant fertilizer treatments included 100 lb N/ac Cal Poly certified organic compost, 100 lb N/ac synthetic CRF and a control treatment (0 lb N/ac). Strawberry cultivars included three UC varieties, ‘Monterey,’ ‘Albion,’ and ‘San Andreas,’ and one Driscoll’s proprietary cultivar. Fruit yield and plant mortality data were collected throughout the growing season. Soil C was measured from soil samples collected in the root zone (6 in) while soil nitrate was measured from pore water samples collected in and below the root zone (6 and 12 in, respectively). Strawberry crop N uptake was determined using destructive plant samples while fruit N concentration was determined from subsamples of harvested fruit taken in April, May, June, and July each year. Although compost application did not significantly affect C sequestration and did not reduce disease incidence, there was no significant difference in total yield between compost and CRF treatments suggesting that compost can substitute for synthetic CRF without negatively affecting yield. There was significantly less plant mortality in control treatments compared with compost and CRF treatments suggesting excessive pre-plant N impacts disease incidence by M. phaseolina but more research is needed to better understand the mechanisms of infection by this soilborne pathogen. Total yield in this experiment was lower compared with statewide averages and crop N concentration was lower compared with the literature which is likely a result of disease pressure. Fruit N concentrations for the cultivars in this study were lower than the conversion coefficient defined by the Ag Order which means growers are removing less N through harvest allowing them more room in their N budget. Based on our results, compost may be substituted for synthetic CRF without negatively affecting yield and perhaps even make desirable soil improvements in this production system. And in fields with significant levels of M. phaseolina in the soil, N applications should be considered as it was seen to impact disease incidence. Keywords: compost, controlled release fertilizer, M. phaseolina, nitrogen uptake, Ag Order 4.0

Corn is one of American agriculture's greatest success stories, where we have witnessed incredible increases in yield potential over the last half-century. However, abiotic stress is still the primary limiting factor preventing plants from reaching their true yield potential. In addition, agriculture is not exempt from the deleterious effects of changing weather patterns and the altered climate our world will face as time progresses. Thus, increasing our understanding of how crops interact with their environment both above and below the soil will be crucial to increasing production on a global scale while maximizing profitability at a local level. Five studies were carried out to quantify the relationship between corn and multiple abiotic factors, including temperature, moisture, and nitrogen. In study one, Corn seed germination as a function of temperature was quantified, and the effects were compared between soybean and cotton, both major agronomic crops in Mississippi. Study two determined the effects of osmotic stress on corn seed germination, and commercial corn hybrids' variability was explored. In study three, functional relationships between temperature and early season growth and development were quantified, and the concept of a simple mathematical model for predicting growth as a function of temperature was explored. Study four exemplified the effects of increasing waterlogging durations from 0 to 14 days and determined critical limits for above and below-ground growth. Finally, in study five, growth, development, and physiology were determined as a function of nitrogen concentration. In addition, optimum concentrations to maximize vigor were estimated. Data generated from these studies exemplify how abiotic stress significantly affects corn during germination and early season growth and development. These datasets will be valuable foundations to build on as we explore how abiotic stress affects all growth stages of corn and other important agronomic crops. Functional relationships generated from these studies will be useful to update crop simulation models. Both simple and complex mathematical models have promising implications in emerging and developing precision and predictive agricultural technologies.

12 N treatments in 2020 and 11 in 2021 were replicated four times over four locations in a randomized complete block design. The first research tested the efficacy of CYG for Mississippi corn (Zea mays L.) production. The optimum N rates were calculated by fitting four models. Differences between the CYG rate and AONR were compared. AONR varied from 134 to 301 kg N ha–1 at different management levels. When we compared the AONR to the CYG rate, the CYG rate over-recommended N in 12 of the 14 possible comparisons. The second study compared different VIs, methods, and sensors at various corn stages to predict in-season yield potential. Relative VI measurements were superior for grain yield prediction. MicaSense best predicted yield at the VT-R1 stages, Crop Circle and SPAD at VT, and GreenSeeker at V10. When VIs were compared, SCCCI outperformed other VIs.