Seven years of biosolids versus inorganic nitrogen applications to tall fescue.

Repeated applications of municipal wastewater biosolids is cost effective for biosolids managers, but may lead to undesirable accumulations of nutrients or contaminants. We evaluated the effects of seven years of biosolids applications on tall fescue (Festuca arundinacea Schreb.) production and nutrient availability. We compared two types of Class A biosolids applied to tall fescue on a sandy loam in western Washington. Mean annual biosolids rates of 290, 580, and 870 kg total N ha(-1) yr(-1) were compared with inorganic N and zero-N controls using a randomized complete block design. We measured yield and N uptake for each forage harvest, plant tissue metals at selected harvests, soil nitrate each fall, diethylenetriaminepentaacetic acid (DTPA)-extractable metals after five years of applications, and soil pH, available P, and organic C after seven years. Forage yields increased with biosolids rate. Apparent nitrogen recovery (ANR) for biosolids averaged 18% in 1993 (Year 1), 35% in 1994, and 46% in 1999. The ANR for inorganic N averaged 62% from 1994-1999. Residual soil nitrate was less than 25 kg ha(-1) for all treatments through 1995, but increased beginning in 1996 for the high biosolids rate. Biosolids increased soil organic C levels by 2 to 5 g kg(-1) and Bray-1 P levels by 300 to 600 mg kg(-1) (0-15 cm depth). Plant tissue Zn increased from 24 to 66 mg kg(-1) at the highest application rate. Nearly all of the DTPA-extractable metals remained in the 0- to 8-cm soil depth.

Relationships among absorbents on the reduction of grass silage effluent and silage quality.

Effluent from grass silage is a threat to water quality and a loss of valuable forage nutrients from dairy farms. Absorbents potentially reduce effluent loss when weather conditions are not ideal for field wilting. The objective was to determine the effectiveness of various absorbents at reducing silage effluent. First-harvest, direct-cut, perennial grass forage was ensiled with and without absorbents in medium-sized experimental silos for 3 consecutive yr. Silos contained 4.54 kg of grass and one of the following feed quality absorbents: 10% rolled barley, 10% dried and pelleted beet pulp, or alfalfa cubes at 10, 20, or 30%. Nonfeed quality absorbents used were 1% starch grafter polymer, 1% bentonite clay, and 10% newspaper. Silage from direct-harvest control forage produced the highest effluent losses, but the wilting of grass prior to ensiling or the mixing of grass with 30% alfalfa cubes nearly eliminated effluent. Silage pH was lowest when rolled barley or beet pulp was used as the absorbent and was highest for wilted grass. Silage dry matter was increased by wilting and by the use of barley, beet pulp, newspapers, or alfalfa cubes as absorbents. The addition of 10% newspaper greatly reduced in vitro dry matter digestibility and crude protein. Increased water-soluble carbohydrate concentrations were found for silage from grass forage treated with rolled barley, beet pulp, or alfalfa cubes prior to ensiling. Although bentonite clay and newspapers reduced effluent losses, greater water-soluble carbohydrate losses were found for these treatments compared with the direct control. Alfalfa cubes were found to be effective absorbents and did not reduce grass silage quality.

In vivo digestibility of corn and sunflower intercropped as a silage crop.

Six nonlactating Holstein cows in a 3 x 3 Latin square total collection digestion trial were used to evaluate three low DM (less than 26%) silage types: 1) corn; 2) corn and sunflower intercropped and 3) sunflower. Feeding periods consisted of a 7-d adjustment followed by a 5-d collection period. Dry matter intake was similar for the three treatments; 12.5, 12.1, and 12.0 kg, respectively. Percent apparent digestibilities for DM, NDF, and N for corn and corn-sunflower were similar and greater than for sunflower: DM (69.6, 68.2, 57.4); NDF (68.1, 61.5, 51.6); and N (66.3, 66.5, 63.6). No differences were observed for digestibilities of ADF, hemicellulose, starch, or for N retention. Percent ether extract digestibility was greatest for corn-sunflower and sunflower silage when compared with digestibility of corn silage (82.5, 77.9, vs. 66.3). Major changes in rumen fermentation patterns were not observed as evidenced by rumen molar proportions of propionate, isobutyrate, isovalerate, valerate, or acetate to propionate ratios. No difference was observed for rumen NH3 N (2.7, 3.2, 4.1 mg/dl, respectively). Corn and sunflower intercropped silage had intermediate concentrations of fat, fiber, and protein when compared with those of corn or sunflower silages.