Robert Flynn

Temperature and Chemical Changes During Composting of Broiler Litter

Composting broiler litter (a mixture of manure, bedding material, and wasted feed) with commonly available high-C substrates may be a viable alternative to reduce current land disposal practices for litter. Broiler litter with wood shavings as a bedding material and broiler litter with peanut hulls as a bedding material were composted with wheat straw, peanut hulls, pine bark and paper mill sludge in 0.33 m3 batch reactors. Litters and C substrates were mixed to achieve C:N ratios of approximately 30:1. Dry weight, total N, total C, temperature, electrical conductivity and pH were determined at regular intervals. Maximum temperatures peaked near 70°C within 2.25 d after mixing peanut hulls with litter and within 2.58 d for pine bark and litter. Composts made from paper mill sludge approached 50°C within 3.71 d. Wheat straw composts never exceeded 40°C which could present potential health problems associated with pathogenic microorganisms. Mass loss and C:N ratio gradually declined and stabilized approxima...

Germplasm evaluation and transfer of Verticillium wilt resistance from Pima ( Gossypium barbadense ) to Upland cotton ( G. hirsutum )

Verticillium wilt (VW, Verticillium dahliae) is a worldwide destructive soil-borne fungal disease and employment of VW resistant cultivars is the most economic and efficient method in sustainable cotton production. However, information concerning VW resistance in current commercial cotton cultivars and transfer of VW resistance from Pima (Gossypium barbadense) to Upland (Gossypium hirsutum) cotton is lacking. The objective of the current study was to report findings in evaluating commercial cotton cultivars and germplasm lines for VW resistance in field and greenhouse (GH) experiments conducted in 2003, 2006, and 2007. In the study, 267 cultivars and germplasm lines were screened in the GH, while 357 genotypes were screened in the field. The results indicated that (1) VW significantly reduced cotton yield, lint percentage, 50% span length and micronaire, but not 2.5% span length and fiber strength, when healthy and diseased plants in 23 cultivars were compared; (2) some commercial cotton cultivars developed by major cotton seed companies in the US displayed good VW resistance; (3) many Acala cotton cultivars released in the past also had good VW resistance, but not all Acala cotton germplasm are resistant; (4) Pima cotton possessed higher levels of VW resistance than Upland cotton, but the performance was reversed when the root system was wounded after inoculation; (5) VW resistance in some conventional cultivars was transferred into their transgenic version through backcrossing; and (6) some advanced backcross inbred lines developed from a cross between Upland and Pima cotton showed good VW resistance. The successful development of VW resistant transgenic cultivars and transfer of VW resistance from Pima to Upland cotton implies that VW resistance is associated with a few genes if not a major one.

New Mexico Blue Grama Rangeland Response to Dairy Manure Application

Abstract New Mexico supports over 290 000 dairy cattle. These cattle produce large quantities of manure. It has been suggested excess dairy manure could be applied to rangelands as an organic fertilizer to increase soil fertility and herbaceous production. Manure was applied June 2000 to a rangeland in New Mexico dominated by blue grama (Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths) according to phosphorus (P) content: a recommended (light) rate (54 kg P·ha−1) to enhance blue grama growth and a gross overapplication (heavy) rate (493 kg P·ha−1) to determine their effects on vegetation. The actual application rate of manure on a dry weight basis was 0, 11 739, and 107 174 kg·ha−1. Four replications of control, light, and heavy rates were established. Herbaceous standing crop (kg·ha−1) was similar 1 growing season after manure application, and greater 2 and 3 growing seasons after application on the light treatment compared with the control. Initially the heavy treatment suppressed herbaceous standing crop; thereafter, standing crop responded in a linear fashion to rainfall. Three growing seasons after manure application, basal cover was similar between light and control treatments, whereas the heavy treatment continued to be characterized principally by manure/litter cover. Heavy disposal-oriented treatments are not suitable for blue grama rangelands because of persistent declines in herbaceous cover and changes in soil salinity. A light manure application rate that is based on P content can increase forb and in particular grass standing crop on arid blue grama rangelands. Successful rangeland manure applications will depend on proper management to insure objectives are met while minimizing any hazards to the environment.

Appropriate Preservation of Dairy Wastewater Samples for Environmental Analysis

Thousands of gallons of water are used in dairies to wash cows before milking and for cleaning equipment. The wastewater generated contains elevated levels of organic matter and pollutants, including nitrogen that once converted, may contaminate groundwater with nitrate. This study was conducted to determine the amount of sulfuric acid needed to preserve wastewater samples from a New Mexico dairy in the southwestern U.S. Titrations of wastewater from a local dairy using full strength (18 M) sulfuric acid were performed to determine the amount of acid needed to bring the pH of the sample to below two, the recommended pH for sample preservation. An average of 0.33 mL of acid was required for every 100 mL of wastewater. Due to sample variability, we recommend that 0.4 mL sulfuric acid be added for every 100 mL dairy wastewater sample to ensure adequate acidification. This quantity is twice the amount currently recommended in U.S. Environmental Protection Agency guidelines.