The objective of this study was to evaluate the impact of maturity at harvest and dietary inclusion rate of triticale silage on the production performance and nutrient utilization of lactating dairy cows. The hypothesis was that the production performance of lactating dairy cows would increase when consuming triticale harvested and ensiled at the boot stage of maturity (BS), as compared to consuming triticale harvested and ensiled at the soft-dough stage of maturity (SDS), and that the difference would be greater in high-forage diets. A single field of triticale was planted, and harvested at the BS or SDS of maturity, and the harvested forage was ensiled in separate bunker silos. Eight primiparous and 16 multiparous Holstein cows were assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design with 21-d periods. Cows were fed once daily (10:00 a.m.) using a Calan gate system (American Calan Inc., Northwood, NH). Diets included BS or SDS triticale silage with dietary forage inclusion of 54% (high-forage; HF) or 36% (low-forage; LF). Cows consuming diets containing BS silage produced more milk per day than cows consuming diets containing SDS silage. This response was observed when feeding both LF and HF diets. The maturity of the forage (BS vs. SDS) did not affect the apparent total tract digestibility of neutral detergent fiber (NDF) or the yield of energy-corrected milk. Cows consuming diets containing BS silage yielded more milk protein and lactose per day than cows consuming diets containing SDS silage, and we also observed this response when feeding both LF and HF diets. When fed the LF diets, cows had a higher apparent total-tract digestibility on CP and NDF, whereas apparent total-tract starch digestibility was higher in cows fed HF diets. Cows consuming LF diets exhibited higher levels of de novo fatty acid synthesis compared to those on HF diets. Feeding LF diets yielded more C14:1, C18:1 trans-9, and unknown fatty acids, while C16:0, C18:1 trans-10, CLA cis-9, trans-11, and CLA trans-10, cis-12 fatty acids yielded more in cows fed with SDS diets. Notably, CLA cis-9, trans-11, and CLA trans-10, cis-12 fatty acids were highest in SDS diets. Additionally, stearic fatty acid (C18:0) concentrations increased in HF diets and SDS silage. In conclusion, the study found that triticale maturity at harvest minimally affects dairy cow performance, with consistent milk production across harvest stages. While nutrient variations were observed, the conclusion emphasizes the importance of considering not only forage quality but also agronomic management and planting schedules for subsequent crops when deciding on harvest timing. / Master of Science / Cool-season or winter annual grasses, also known as small grain grasses, can be cultivated as cover crops to protect or improve the quality of the soil when the warm-season primary crop (e.g., corn) is not growing. These crops are grown during intervals between regular crop production periods. In the context of cover cropping in the United States, small grains are planted during the fall and winter seasons. One of these small grain crops is triticale, a hybrid resulting from the crossbreeding of wheat and rye. Whole plant triticale is ideal for preservation by ensiling due to its high level of water-soluble carbohydrates, low buffering capacity, and easily controllable moisture content. The objectives of this study were to evaluate the impact of harvesting maturity and dietary inclusion rate of whole plant triticale silage on milk production performance and nutrient utilization of lactating dairy cows. The hypothesis was that the production performance of lactating dairy cows would increase when consuming triticale harvested and ensiled at the boot stage of maturity (BS), as compared to consuming triticale harvested and ensiled at the soft-dough stage of maturity (SDS), which is more advanced in maturity. A single field of triticale was planted, harvested at either BS or SDS and ensiled in separate bunker silos. Twenty-four Holstein cows were grouped by days in milk and daily milk production in groups of 4 cows each, and each group was assigned to one of four experimental diets. Regardless of inclusion rate, cows consuming BS diets yielded more milk, milk protein, and lactose than did cows on SDS diets and for milk yield, we observed this response when feeding both LF and HF diets. The maturity at harvest did not affect dry matter, crude protein, neutral detergent fiber, or starch digestibility of the diets. Crude protein and neutral detergent fiber digestibility were higher in cows consuming low-forage diets than in cows consuming high-forage diets, whereas starch apparent total-tract digestibility was higher in cows fed HF diets. In conclusion, the study found that triticale maturity at harvest minimally affects dairy cow performance, with consistent milk production across harvest stages. While nutrient variations were observed, the conclusion emphasizes the importance of considering not only forage quality but also agronomic management and planting schedules for subsequent crops when deciding on harvest timing.

Two wheat varieties were grown in Graham county as a follow -up to a previous field demonstration. AC79-97, a red wheat developed by the University of Arizona for the Safford area, yielded 6719 pounds per acre, compared with 6359 pounds per acre for Super-X. The protein differential made the crop values even more important than the yield comparison. AC79-97 produced $454 per acre, compared to $423 for Super-X. Using two year's data, AC79-97 produced 85 more pounds of protein per acre than Super-X, with a protein supplement replacement value of $28 per acre.

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A greenhouse experiment was conducted at the University of Arizona, Tucson, Arizona, to study the effects of liquid sewage sludge loading rates on the vegetative growth, yield, and quality of barley grain and straw. Vegetative growth, grain yields, and straw yields were similar whether barley was grown with inorganic N or equivalent amounts of plant-available N from sewage sludge. Sewage sludge loading rates higher than three times the recommended plant-available N rate decreased barley stands in the seedling stage. The loss of stand was compensated for by higher tillering later in the season. High sludge loading rates tended to delay maturity, increase tillering and increase straw yield; however, they did not affect grain yield. Concentrations of cadmium (Cd), copper, (Cu), lead (Pb), nickel (Ni), and zinc (Zn) in barley grain and straw and the amounts of heavy metals recovered in the soil following each harvest were similar to the control for all sewage sludge treatments.

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Attempts to characterize nitrogen (N) status of irrigated spring wheat by using basal stem nitrate - N (NO₃⁻N) tissue tests have shown contradictory results, due to the wide range of agronomic conditions existing in Arizona. Seven N fertility trials were conducted at the Maricopa and Safford Agricultural Centers over the 1985-88 crop years to examine the effects of N rate, N fertilizer form, residual soil N, soil texture and contrasting varieties on basal stem NO₃⁻N concentrations, yield and quality of irrigated durum wheat. Fertilizer N treatments were broadcast at planting then at the 5-6 leaf, boot and anthesis growth stages to simulate fertigation in conjunction with the first four basin irrigation events. Stem tissue samples were taken from all plots at the 3-4 leaf 5-6 leaf joint, boot and anthesis growth stages for NO₃⁻N analysis with a nitrate electrode. Diagnostic levels for durum wheat basal stem tissue NO₃⁻N tests at these growth stages are presented.

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.