Hay Yield Determinations of Mixed Swards Using a Disk Meter¹

Abstract

Estimates of hay yields are frequently desirable for purposes of measuring fertilizer response, studying effects of management and cultural practices, and determining animal units that can be maintained on forage produced from a given area. Estimates of forage yield can be obtained by cutting and weighing, but the random collection of forage samples for estimating yields is not a viable alternative in some cases. A convenient, quick, and accurate method of determining forage yields in situ would benefit research workers and those involved in commercial and extension agriculture operations. The purpose of this investigation was to determine the suitability of using a disk meter to estimate dry matter yield of mixed swards. A 0.5m2 disk meter was constructed from hardboard paneling, steel pipe, and a flange. Paired disk meter readings and dry matter yields from clipping were taken from 708 swards used for hay production in 1978. Swards consisting of cool season grasses, legumes, and weeds were characterized into 14 categories according to species composition and growth stage. Regression equations were determined for each category from paired disk readings and dry matter yields from clippings. The slopes of the regression lines for the different categories were not significantly different. The coefficient of determination (r2) was 0.82 when using a single regression line for all categories. The points of intercept of the regression lines on the vertical axis for the different categories were different with a definite trend for regression lines for first cutting swards to intercept higher than regression lines for aftermath. The formula which best described the relationship between disk reading and yield was: yield estimate = intercept for category + 183 (disk reading) − 1.73 (disk reading)2. In order to test the disk meter and formula method, yields on 40 swards were determined independently using two methods. The correlation coefficient between sward yields estimated using the disk meter and formula and sward yields estimated using weighed clippings was +92.

An evaluation of the drop‐disc technique for measurements of herbage production in ryegrass for silage

“…1991. S and L were similarly well correlated with DM.DiscussionThe scatter of calibration data(Figure 1)shows a curvilinear trend similar to that reported byEarle and McGowan (1979) andBaker et al (1981). The curve was most pronounced between S values of 150 and 200 mm.…”

A Simple Disc Meter for Measurement of Pasture Height and Forage Bulk

“…1962) to&borate mechanismswhichemploycounters and gears to automatically determine and record the resting height ofametal plate (Earleand McGowan 1979). Most numerous ofall, however, are "disc meters" employing circular plates constructed from wood (Baker et al 1981) or metal (Castle 1976, Powell 1974, Santillan et al 1979). These devices, while generally useful to determine forage bulk.…”

Use of a Disk Meter to Evaluate Continuously Grazed Pastures

“…BRANS-BY et al (1977) recommended frequent calibration throughout the season for pasture. BAKER et al (1981), however, found no difference in the slope of the regression line between DMH and DM due to either species composition or growth stage for hay crops. The intercept was, however, different for different growth stages.…”

“…There is no agreement in the literature concerning the effect of plant species, growth stage, botanical composition, etc., on the relationship benveen DMH and DM (BAKER et al 1981, BRANSBY et al 1977, LOPEZ 1980. BRANS-BY et al (1977) recommended frequent calibration throughout the season for pasture.…”