abstract: Alfalfa is a major feed crop widely cultivated in the United States. It is the fourth largest crop in acreage in the US after corn, soybean, and all types of wheat. As of 2003, about 48% of alfalfa was produced in the western US states where alfalfa ranks first, second, or third in crop acreage. Considering that the western US is historically water-scarce and alfalfa is a water-intensive crop, it creates a concern about exacerbating the current water crisis in the US west. Furthermore, the recent increased export of alfalfa from the western US states to China and the United Arab Emirates has fueled the debate over the virtual water content embedded in the crop. In this study, I analyzed changes of cropland systems under the three basic scenarios, using a stylized model with a combination of dynamical, hydrological, and economic elements. The three scenarios are 1) international demands for alfalfa continue to grow (or at least to stay high), 2) deficit irrigation is widely imposed in the dry region, and 3) long-term droughts persist or intensify reducing precipitation. The results of this study sheds light on how distribution of crop areas responds to climatic, economic, and institutional conditions. First, international markets, albeit small compared to domestic markets, provide economic opportunities to increase alfalfa acreage in the dry region. Second, potential water savings from mid-summer deficit irrigation can be used to expand alfalfa production in the dry region. Third, as water becomes scarce, farmers more quickly switch to crops that make more economic use of the limited water. / Dissertation/Thesis / Masters Thesis Sustainability 2015

Made available in DSpace on 2014-06-11T19:27:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-23Bitstream added on 2014-06-13T20:56:38Z : No. of bitstreams: 1 martins_mb_me_botfmvz.pdf: 732603 bytes, checksum: aaa29421580edf9cbe7e5d86e1091b6f (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / Este trabalho objetivou avaliar o turnover e a meia-vida do carbono nas fezes e sangue de ovelhas alimentadas com plantas C3 e C4, pela técnica dos isótopos estáveis. Oito ovelhas da raça Santa Inês, após um período de adaptação de 45 dias recebendo 50% de feno de alfafa e 50% de silagem de milho, foram distribuídas ao acaso em dois tratamentos: o primeiro consistiu de animais que receberam feno de alfafa (C3-FA) e o segundo, dos animais que receberam apenas silagem de milho (C4-SM). Para mensurar o turnover de carbono (substituição isotópica) nas fezes e sangue em determinado intervalo de tempo, foi utilizada a função exponencial do tempo. Apenas os valores isotópicos das fezes atingiram o patamar de equilíbrio, indicando valores de meia-vida de 1,2 e 1,0 dias para os tratamentos C3-FA e C4-SM, respectivamente. Já no sangue, o tempo de coleta dos dados (104 dias) foi insuficiente para encontrar o patamar de equilíbrio isotópico, indicando uma troca de carbono lenta. De acordo com os resultados deste estudo, pode-se concluir que o sangue apresenta turnover lento indicando o sinal isotópico de dietas antigas; e as fezes, turnover rápido, indicadas para refletir dietas recentes, próximas da fase de avaliação / The aim of this work was to evaluate the carbon turnover and half-life on feces and blood sheep, fed on C3 and C4 plants, using the stable isotopes technique. Eight Santa Ines sheep, after 45 days as adjustment period receiving 50% of alfalfa hay and 50% of corn silage, were randomly assigned to two treatments: the first one the animals fed on alfalfa hay (C3-FA) and the second one the animals fed on only corn silage (C4-SM). The time exponential function was used to measure the carbon turnover (isotope substitution) on feces and blood in a certain period of time. Only the isotope feces values reached the plateau value, indicating half-life of 1.2 and 1.0 days for C3-FA and C4-SM treatment, respectively. The data collection time (104 days) for blood was not enough to find a plateau isotope, indicating a slow carbon exchange. So we can infer that the blood has a slow turnover, indicating isotopic signal of ancient diets; and the feces showed a fast turnover, being used to reflect recent diet, next to the evaluation period

2 p. / Alfalfa varieties differ in fall dormancy, defined as growth during the fall. Nondormant alfalfa varieties are usually planted in mild winter areas for their ability to grow in the fall. However, fall growth of nondormant alfalfa may be undesirable in areas subject to repeated frosts or freezes. Nondormant, very nondormant, and extremely nondormant alfalfa varieties (fall dormancy class 8, 9, and 10) are adapted to elevations below 4000 feet in Arizona. Other dormancy classes not included in this publication are moderately nondormant varieties (fall dormancy class 7) which may be grown from 3000 to 5000 feet, and semi-dormant and dormant varieties (fall dormancy 6 and below) which are adapted to colder winter areas above 4000 feet.

A major design issue in the implementation of a Subsurface Drip Irrigation (SDI) system for extensively crops such as alfalfa (i.e. crops that cover the entire surface as opposed to row crops), is the determination of the appropriate depth of placement of the drip line tubing. It is important to allow necessary farming operations with heavy equipment at harvesting times while still providing adequate water to meet the crop water requirements. It is also a need to ensure appropriate spacing between the dripline laterals to assure reasonable lateral irrigation uniformity for plant germination. In this study, the program HYDRUS-2D was used to determine the wetting pattern above and laterally from a subsurface drip emitter of an SDI system, for three soils typically found in Southern California and Arizona, a Sandy Clay Loam (SCL), a Clay Loam (CL) and a Loam (L). The design and management conditions from an experimental alfalfa field with an SDI system located at Holtville CA were used and analyzed. The first irrigation design was with a drip line depth of placement of 30 cm and the second design with an installation depth of 50 cm. The two different irrigation management schemes utilized by the farmers and producers in that area were: one with a running time of six hours and a frequency of every three days and the second one with an irrigation running time of twenty-four hours with a frequency of seven days or irrigation every week. After having carried out the analysis and studies of the irrigation designs and management schemes mentioned above, a new model with its corresponding management was proposed to meet the alfalfa water requirements under that particular field and weather conditions while we ensure a sufficiently dry soil surface at harvesting time for each soil case. This irrigation management includes twelve hours or irrigation every three days, for each of the three soils analyzed. It was found that the vertical rise of water above the emitters on the day of the cut, for our recommended SDI management was 26 cm, 29 cm, and 27 cm, with a moisture content at the soil surface of 14.9%, 24%, and 13% for the SCL, CL, and L soils respectively. Then, through the utilization of classical soil mechanics theory, an analysis to calculate the increase in stress on soils at any depth due to a load on the surface from a conventional tractor used during harvest operations was made for the proposed SDI system. The results from the increase in stress were then used together with soil strength properties such as shear strength as a function of soil moisture content to determine the minimum allowable depth of placement of the drip line tubing to ensure that soil failure does not occur. The load increase from a 3,300-kg four-wheel tractor was found to be 0.59 kg/cm2 under a rear tire at 10 cm below the surface and 0.07 kg/cm2 at 70 cm below the surface. To ensure that shearing failure does not occur, a stress analysis using Mohr’s circle indicated that the soil moisture content at 10 cm below the surface should be no greater than 26.8%, 32.7%, and 27% in the SCL, CL, and L soils respectively. The mimimum moisture content of 26.8% occur at 10 cm above the drip line for a SCL soil, which means that the minimum depth placement to avoid failure would be 40 cm below the surface. A similar analysis for the CL and L yielded minimum installation depths of 35 cm and 40 cm respectively. This type of analysis is useful in determining the depth of placement of SDI drip line tubing to ensure adequate trafficability of soil irrigated with subsurface drip irrigation systems. An additional outcome of the modeling study was the determination of the lateral extent of the wetted zone which can be used to determine the appropriate lateral spacing between drip line tubing. Thus, to ensure adequate spatial coverage by a subsurface drip system, the maximum horizontal spacing should be of 80 cm for SCL and L soils and 90 cm in CL soils.

Thesis (MSc. Agriculture (Animal Production)) -- University of Limpopo, 2015 / A series of experiments were carried out to investigate the effect of replacing calf starter feed with lucerne leaf-meal (LLM) on diet intake, rumen degradation and growth of Holstein heifer calves. The treatments were calf starter pellets (PEL), a mixture of 65% calf starter concentrate pellets and 35% LLM (P65L35), and a mixture of 50% calf starter concentrate pellets and 50% LLM (P50L50). The first part of the study determined nutrient composition of lucerne leaf-meal (LLM), calf starter pellets and lucerne leaf-meal substituted diets. The experimental design was a completely randomised design (CRD). Lucerne leaf-meal had high protein (25% DM) and gross energy (GE) (16.2 MJ/kg DM) levels; low starch (0.2% DM) and fibre fractions. All diets had similar (P>0.05) crude protein (CP) and GE values. The concentrate diet was higher (P<0.05) in starch, ether extracts and fibre bound CP (neutral detergent insoluble crude protein). The second part of the study estimated the supply of energy and protein fractions and carbohydrate composition from LLM and the diets. A CRD was used. Lucerne leaf-meal had high energy density and protein supply with low unavailable fibre and protein contents. All the treatments had TDN above 80%. Non-fibre carbohydrate levels differed (P<0.05) across treatments. The energy fractions were similar (P>0.05) across all dietary treatments. However, Diets P65L35 and P50L50 had higher (P<0.05) soluble and non-fibre carbohydrates than PEL diet. The third part of the study determined in vitro degradation of LLM and the three dietary treatments using the ANKOM DaisyII incubator system. Lucerne leaf-meal had high in vitro dry matter (IVDMD), organic matter (IVOMD), crude protein (IVCPD) and neutral detergent fibre (IVNDFD) degradation. All diets had similar (P>0.05) IVDMD and IVOMD at 0, 4, 10 and 48 hours of incubation. Higher (P<0.05) IVNDFD, IVCPD and effective degradation (ED) were observed in Diets P65L35 and P50L50 than in Diet PEL. No differences (P>0.05) in IVNDFD and IVCPD were observed at 24 and 48 hours of incubation. The rate of degradation (‘c’) was similar (P>0.05) across all the diets. The data demonstrated that LLM diets had higher (P<0.05) degradation values than Diet PEL. vi The fourth part of the study determined the effects of replacing calf starter pellets with lucerne leaf-meal on diet intake, feed conversion ratio and growth of pre-weaned (21 to 42 days old calves) and transition (43 to 56 days old calves) Holstein heifer calves. The experimental design was a completely randomised design, with a total of 24 calves housed in individual pens. This study was divided into two experimental phases, namely, pre-weaning (Experiment 1) and transition (Experiment 2) phases. In each experiment, different calves were used. Body weights were taken weekly. The balance of ruminal nitrogen (% RNB) was predicted using Large Ruminant Nutrition System (LRNS) model. In Experiment 1 calves had free access to clean water and fed 4 litres/calf/day of unpasteurised milk. During the pre-weaning phase, differences (P<0.05) were observed in solid feed dry matter (DM), crude protein (CP), neutral detergent fibre (NDF) and starch intakes with Diet P50L50 having higher (P<0.05) intakes than Diets PEL and P65L35. Similarly, higher (P<0.05) % RNB and daily weight gains (ADG) were observed with calves on Diet P50L50. However, calves had similar (P>0.05) initial and final weights and feed conversion ratio (FCR). Calves in Experiment 2 were fed 2 litres/calf/day of unpasteurised milk. Calves were weaned at the age of 56 days. During the transition phase, calves on Diet HP50L50 had higher (P<0.05) CP intake and % RNB than those on HPEL and HP65L35 diets. However, higher (P<0.05) solid feed starch intake was observed with calves on Diet HPEL. All dietary treatments had similar (P>0.05) DM intake, initial and final live weights, ADG and FCR. The fifth part of the study predicted diet concentrations of Holstein heifer calves under specific conditions using the level 1 solution of Large Ruminant Nutrition System (LRNS) model. During the pre-weaning phase, P65L35 and P50L50 diets indicated higher (P<0.05) energy density values than Diet PEL. However, all diets had similar (P>0.05) metabolisable energy levels. No differences (P>0.05) in net energy for maintenance (NEm) and gain (NEg) during the transition phase were observed. However, Diet HPEL had higher (P<0.05) apparent TDN and ME levels compared to other dietary treatments. Diets P65L35 and P50L50 had higher (P<0.05) protein, energy density and degradation values than Diet PEL. It is concluded LLM inclusions in the calf diet improved Holstein heifer calves’ performance. / Agricultural Research Council (ARC)

<div>Fresh produce has been the leading source of foodborne illness outbreaks in the US, surpassing typical pathogen carriers such as meat, dairy, and seafood. Among the fresh produce popular to the consumers, cantaloupe and sprouts are mostly susceptible to pathogen contaminations and outbreaks. However, it has been a challenge to address the key factor in the contamination - the biofilms formed by pathogens are highly resistant to conventional washing and cleaning procedures. For cantaloupe, the net-like and porous surface forms a barrier for washing. For sprouts, the fragile texture of seedlings prevents aggressive cleaning operation and biofilm removal.</div><div><br></div><div>In this study, innovative interventions were developed to improve microbial safety of fresh produce, using cantaloupe and alfalfa sprouts as models. For cantaloupe, abrasive brushing was designed to remove pathogen biofilm from cantaloupe. Our research found pathogens could form biofilm at cantaloupe rind surface as the residence time of pathogens increased. Biofilm formed on cantaloupe rind was imaged by cryo-scanning electron microscopy (cryo-SEM), and its resistance to sodium hypochlorite and lauroyl arginate ethyl (LAE) was confirmed. Furthermore, abrasive brushing with peroxyacetic acid (PAA) could effectively remove biofilm formed at cantaloupe rind. The efficacy of this novel cleaning technique was highly desirable, which could achieve 3 log reduction in pathogen population. Mechanism of abrasive brushing to remove biofilm at cantaloupe rind surface was also proposed. Conceivably, brushing with diatomaceous earth (DE) and PAA could be an innovative and cost-effective method to remove pathogen biofilm from cantaloupe rind.</div><div><br></div><div>For alfalfa sprouts, since most of the outbreaks are linked to the sprouting seeds, seed disinfection treatments are considered to be the most effective method to improve microbial safety of sprouts. In this study, a newly developed alginate-based, antimicrobial seed coating treatment was evaluated for its efficacy to reduce foodborne pathogens from alfalfa seeds and sprouts. The calcium alginate coating in the presence of 2.5% lactic acid (CA-LA coating) reduced foodborne pathogens inoculated on alfalfa seeds to an undetectable level on day 1 during 28 day-seed storage, while chlorine (20,000 ppm) or lactic acid (2.5%) treatment took longer time to reach the same level. With sprouts, CA-LA coating resulted in > 2.5 log reduction for pathogen cells. In contrast, log reduction was < 0.6 for either chlorine (20,000 ppm) or lactic acid (2.5%) treatment. In general, this study indicated the effect of calcium alginate coating on reducing bacterial load of alfalfa seeds and sprouts, however, the germination rate of treated seeds was compromised due to the addition of lactic acid in the seed coating. Further study is needed to select antimicrobial compounds with minimum impact on germination rate of seeds.</div><div><br></div>

Alfalfa is the most important forage crop in Utah. It is of particular importance to the Uintah Basin, Utah area where alfalfa hay and seed production are major sources of agricultural income. This crop owes much of its popularity to the fact that it will normally produce large yields of good forage on land which is unsuited to more intensive cultivation. In many cases it is impractical to advocate disease control practices which involve extra labor or expense and as a result most diseases of alfalfa, if controlled at all, are controlled by the use of resistant varieties. During the past few years alfalfa witches' broom has become detrimental in the Uintah Basin area. This disease shortens the length of life of alfalfa stands and reduces the yield. Some diseased stands are killed out in a period of three years. It is difficult and expensive to reestablish alfalfa in this area where water supplies are usually low. Therefore, it is imperative that alfalfa stands remain in production for several years. These problems justify a study to find resistance to alfalfa witches' broom. The objectives of this study are to select varieties of alfalfa which are resistant to alfalfa witches' broom in the Uintah Basin area, to select varieties of alfalfa which are best adapted to the area for high yield per acre, to determine which of a few insects tested are responsible for transmission of alfalfa witches' broom virus, and to determine if certain dodder species (Cuscuta spp.) act as transmission bridges for alfalfa witches' broom.

Selections in Du Puits alfalfa (Medicago sativa L. ) were evaluated for saponin content. The data obtained from the Trichoderma bioassay were converted to saponin values by regressions and standard curves. It was necessary to adjust the concentration of alfalfa extract in the bioassay so that the saponin content in alfalfa was estimated in that portion of the curve showing a marked response to saponin. A different regression was established for each group of low and high saponin plants of Du Puits alfalfa. The standard curve prepared with extract of Du Puits alfalfa used on the basis of its saponin content or the commercial purified saponin could be utilized for estimating the saponin content in Du Puits alfalfa, because the results were comparable to the values determined by chemical analysis. Attention should be given to the concentration of extract used when converting the bioassays to actual saponin content, because certain concentrations gave values more similar to the chemical analysis than others. Two cycles of selection for low and high saponin content in Du Puits alfalfa were involved in the tests. The results indicated that the saponin content in low saponin plants was lower and that the saponin content in the high saponin plants was higher than in the unselected plants. They also showed that average saponin values in low and high saponin and the unselected plants were similar between the second and the third cuttings, but different from the first cutting

Water was applied to swaths of cut alfalfa forage with oscillating sprinklers to stimulate rain damage to field drying alfalfa hay to determine the changes in chemical composition, loss of yield, and acceptability of rain damaged hay to sheep. An additional objective was to develop models to estimate yield losses form experimental hay. The experimental hay was prepared with a 2x2x4x4x2 factorial design. The factors were two different cuttings (July and September), two width of swath (3.05 m and 4.27 m), four times of applying artificial rain (3h, 8h, 13h, and 24h after cutting), four levels of artificial rain (no rain, 12.5 mm, 25.0 mm, and 50.0 mm), and two applications of artificial rain (initially and repeated 24h after first application). The hay was dried in favorable weather conditions during the summer season. Fair weather, was observed in the fall season. Chemical composition of the fresh forage at each of the seasons of cutting was closely comparable. Main factors (cut, swath width, time, level, and application of water) and their respective interactions (cut x swath, cut x time, cut x level, time x level) affected chemical composition and voluntary intake of the experimental hay. Samples were analyzed for dry matter, ash, crude protein, plant cell walls, hemicellulose, cellulose, lignin, and acid detergent fiber. No significant changes in the chemical composition occurred when the artificial rain was applied on the fresher forage (<3h after cutting). However, substantial losses were observed after the forage wilted (>13h after cutting). Plant cell contents (100% minus plant cell wall %) decreased while plant cell wall constituents increased with increasing levels of water applied after cutting, and with double application of water. Cell wall content of the hay increased more from rain damage during the fall season than during summer period. Most of the loss of soluble components (cell contents) occurred with the initial application (12.5 mm) of water. Protein content proved to be a poor indicator of rain damage in alfalfa hay. The width of the swather used to harvest the hay (P<.0001), and amount of water applied (P<.0001) were negatively correlated with voluntary intake by lactating ewes. Models for estimating loss of yield from the experimental hay were developed. The amount of rainfall and other descriptive factors were useful to estimate of yield from specific lots of rain damaged alfalfa hay.

This experiment was conducted to determine the effects of corn silage hybrids and nonforage fiber sources (NFFS) in high forage diets formulated with high dietary proportion of alfalfa hay (AH) and corn silage (CS) on ruminal fermentation and productive performance by early lactating dairy cows. Eight multiparous Holstein cows (4 ruminally fistulated) averaging 36 ± 6.2 d in milk were used in a duplicated 4 × 4 Latin square design experiment with a 2 × 2 factorial arrangement of treatments. Cows were fed 1 of 4 dietary treatments during each of the four 21-d periods. Treatments were: 1) conventional corn silage (CCS)-based diet without NFFS, 2) CCS-based diet with NFFS, 3) brown midrib corn silage (BMRCS)-based diet without NFFS, and 4) BMRCS-based diet with NFFS. Diets were isonitrogenous and isocaloric. Sources of NFFS consisted of ground soyhulls and pelleted beet pulp to replace a portion of AH and CS in the diets. In vitro 30-h NDF degradability was greater for BRMCS than CCS (42.3 vs. 31.2%). Neither CS hybrids nor NFFS affected intake of DM and nutrients. Digestibility of N, NDF, and ADF tended to be greater for cows consuming CCS-based diets. Milk yield was not influenced by CS hybrids and NFFS. However, a tendency for an interaction between CS hybrids and NFFS occurred with increasing milk yield due to feeding NFFS with the BMRCS-based diets. Yields of milk fat and 3.5% FCM decreased when feeding the BMRCS-based diet, and there was a tendency for an interaction between CS hybrids and NFFS by further decreased milk fat concentration because of feeding NFFS with BMRCS-based diet. Although feed efficiency (milk/DM intake) was not affected by corn silage hybrids and NFFS, there was an interaction between CS hybrids and NFFS because feed efficiency increased when NFFS was fed only with BMRCS-based diet. Total VFA production and individual molar proportion were not affected by diets. Dietary treatments did not influence ruminal pH profiles except that duration (h/d) of pH < 5.8 decreased when NFFS was fed in CCS-based diet but not in a BMRCS-based diet, causing a tendency for an interaction between CS hybrids and NFFS. Overall measurements in our study reveal that high forage NDF concentration (20% DM on average) may eliminate potentially positive effects of BMRCS. In the high forage diets, NFFS exerted limited effects on productive performance when they replaced AH and CS. Although the high quality AH provided adequate NDF (38.3% DM) for optimal rumen fermentative function, the low NDF concentration of the AH and the overall forage particle size reduced physically effective fiber and milk fat concentration.