Forage Tissue Research Articles

A Field Study of the Agricultural Use of Sewage Sludge: III. Effect on Uptake and Extractability of Sludge‐Borne Metals

AbstractMetal concentrations in soil and plant tissue resulting from land application of liquid digested sewage sludge were examined by determining Cu, Zn, Cd, Ni, and Cr in rye (Secale cereale L.) and sorghum‐sudan (Sorghum bicolor L. Moench × S. sudanese P. Stapf.) forage tissue, in corn (Zea mays L.) grain and stover, and DTPA‐extractable metals in soil. Four crops were grown successively after the application of up to 60 metric ton/ha (dry solids basis) of liquid sewage sludge on a sandy loam and a silt loam in Wisconsin. In general, the addition of sludge increased the concentrations of Cu, Zn, Cd, and Ni in the vegetative tissue but, except for Zn, the additions had relatively little effect on the metal content of corn grain. Chromium did not accumulate in the tissue or grain. In all cases, concentrations of metals were below levels considered to be toxic to the crops grown. Total recovery of added metals by the four crops was < 1% for Cu, Cd, Ni, and Cr, and 1 to 3% for Zn. Levels of DTPA‐extractable Cu, Zn, Cd, and Ni, but not Cr, increased with sludge treatment. Regression analysis showed that DTPA might be useful as a predictor of metal concentrations in the vegetative portions of the plant. However, the relationships were not the same for different crops. The decreases in metal concentrations in the plant tissue and in DTPA extracts with successive crops indicated reversion to less available forms for Zn, Cd, and possibly Ni. The ratio of Cd:Zn in the tissue was about one‐third that of the sludge for all crops.

Ultrastructure of rigid and lignified forage tissue degradation by a filamentous rumen microorganism.

A small (less than 1 mum)-filamentous, branching microorganism was observed in Gram-stained smears of the rumen microflora and was found to degrade tissues in forage samples incubated in vitro and in vivo with rumen fluid and observed by scanning and transmission electron microscopy. The microbe had prokaryotic cytoplasmic features and a gram-positive type of cell wall structure. Round to oval bodies apparently attached to hyphae resembled the sporulation pattern reported for Micromonospora. Filaments and rod and coccal forms of the microbe degraded rigid forage cell walls and lignified, thick-walled sclerenchymal cells. Location of the microbe at a slight distance from the degraded zones suggested the action of extracellular enzymes. The presence of a microbe with the capability of degrading lignified tissue represents an important and unique function in the rumen ecosystem.

Automated Hydrolysis of Nonreducing Sugars and Fructosans from Plant Tissue1

Analytical procedures for chemical analysis of carbohydrates by measuring reducing power before and after hydrolysis, have been automated once the carbohydrates have been removed from the plant tissue. Sugars and fructosans were removed from forage tissue by hot water treatment. Reducing sugars in an aliquot were assayed by automated procedures without acid hydrolysis. Total water‐soluble carbohydrates were measured with automated acid hydrolysis of the same aliquot. Nonreducing carbohydrates were calculated as the difference between total water‐soluble carbohydrates and reducing sugars. Sucrose and fructosan were completely hydrolyzed during the 2 min. exposure to 0.2 N acid at 95 C that were the conditions in automated hydrolysis. However, starch, if present in the water solution, was not broken down by the automated hydrolysis procedure due to low acid concentration and short duration of exposure to heat.Automated procedures increased lab efficiency, reduced routine errors, and eliminated filtration, pipetting, and manual dilution often required by most procedures.

Oven Drying of Small Herbage Samples1

AbstractThe method of preservation of forage tissue may influence the quality and quantity of the product. Oven drying with hot air is widely used; however, enzyme activity and respiration are stimulated during the moisture reduction process. Criterion for selecting efficient drying conditions, such as sample density, kind of container (cloth or paper), and size of container were investigated using alfalfa (Medicago sativa L.) herbage. The dry matter, total nonstructural carbohydrate (TNC), starch, reducing sugar, and nonreducing sugar percentages were related to drying rate.Drying rate was linear until 80% dry weight was reached. Conditions requiring no more than 15 hours to reach 80% dry wt (density of 12 g dry wt per liter for paper sacks) were needed to hold loss within limits of experimental error for estimation of dry weight percentage. The TNC in all oven‐dried samples was less than in freeze‐dried tissue; however, data from cloth bags showed less loss and carbohydrate interconversion than paper sacks. Conditions requiring no more than 8 hours to reach 80% dry wt (density of 7 g per liter for paper sack) were required for sufficiently rapid drying to limit loss and interconversions of nonstructural carbohydrates within limits of experimental error. About twice this density was acceptable if cloth bags were used since the drying tune was reduced by about one‐half with cloth as compared to paper containers that had equal densities. Acceptable bulk densities will differ with efficiency of the drying equipment, but time needed for drying to 80% dry wt should not exceed these limits.

Silica Concentrations in Grazed and Ungrazed Forage Species1

AbstractThe presence of silica (SiO2) has been reported as significantly affecting the nutritional value of forages. This study was conducted to determine the SiO2 concentration in forage samples collected monthly from 2‐ha paddocks of ungrazed tall fescue (Festuca arundinacea Schreb.) and ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) as they matured, and to determine the monthly SiO2 concentrations of vegetative tall fescue, tall fescue‐‘Ladino’ clover (Trifolium repens L.), orchardgrass (Dactylis glomerata L.), orchardgrass‐Ladino clover, Coastal bermudagrass, and stockpiled tall fescue which were incorporated into four grazing systems. Samples representative of forage grazed by yearling beef heifers were collected monthly from caged areas to determine the SiO2 levels.The SiO2 concentrations ranged from 0.30 to 2.65% in dry matter and exhibited variations between species and from month to month within a given species. Silica accumulated rapidly in the forage tissue early in the growing season and thereafter concentrations remained relatively constant. Actively growing forages maintained in a vegetative state by grazing did not exhibit appreciable monthly differences in SiO2 concentration. Increases in SiO2 concentration were noted during winter dormancy. These results indicate the need for further study of the hypothesis that SiO2 can be used to reveal the nutritive value of a forage, particularly the nutritive value of grazed forages.

Influence of added limestone and fertilizers upon the micro-nutrient content of forage tissue and soil

Five rates of limestone and 4 rates of fertilizers were used in a split-plot design to study their effects under field conditions on Mo, Cu, B, Mn, and Zn levels in mixed forage tissue and soil, and on the forage yield. An increase in soil pH resulted in an increase in Mo and Cu content of plant tissue while B, Mn, and Zn decreased. The micro-nutrient content of the tissue increased as the harvesting season progressed. Increasing rates of applied fertilizer did not affect the micro-nutrient content of the forage tissue or soil.