Stocking rate is a key management variable in determining productivity and profitability of grazing systems, but it has not been adequately researched in the USA with high producing dairy cows. A replicated farmlet study was conducted to investigate the potential for improving dairy profitability through increasing stocking rates without influencing milk yield per cow. The study was conducted at the Pennsylvania State University Dairy Research and Education Center in University Park, on pasture dominated by orchardgrass (`Dactylis glomerata L.) and Kentucky bluegrass (Poa pratensis L.). Forty‐eight high‐producing Holstein cows (Bos taurus) were rotationally grazed at seasonal stocking rates of 1.0 (low, LSR), 1.3 (medium, MSR), and 1.6 (high, HSR) cows/acre, and were fed grain at the rate of approximately 1 lb grain DM to 4 lb milk production during a 2 yr study. Stocking rate had a positive effect on pasture nutritional quality, particularly when growth was more vigorous, and had a negative relationship with the percentage of the pasture rejected by cows. Seasonal milk yield per cow (approximately 10 000 lb) and milk composition were not affected by treatments in either year. Consequently, milk production per acre was directly related to stocking rate. An economic analysis of costs and returns indicated that profits per unit area of land increase with stocking rate—a $481/acre advantage was shown for the HSR over the LSR. In contrast, profits per cow decrease with stocking rate—the LSR showed a $36/cow advantage over the HSR. The optimal stocking rate for a given farm therefore will depend on individual farm resources (e.g., land, buildings, cows, etc.), and can be adjusted to meet the constraints of those resources without fear of significant adverse economic impact. Research Question Stocking rate, defined as the relationship between the number of animals and the grazing management unit used over a specified time (a grazing season, for example), is key to determining the potential for production and the profitability of a grazing system. The objective of this trial was to compare forage production and quality, milk production, and profitability on a per cow and per acre basis for three different stocking rates, using high‐producing Holstein cows grazing grass pasture. Literature Summary Where pastures are the primary source of feed for dairy cows, research consistently has shown that stocking rate is a major factor in determining the efficiency of the system. It determines the amount of the pasture that is available per cow, the proportion of the pasture that is consumed, and also influences the quality and long‐term productivity of the sward. Stocking rate is a crucial variable in New Zealand because pasture systems there are designed to maximize returns per acre. In contrast, dairy production in the USA traditionally focuses on returns per cow, and even where pastures are used, concentrates and supplemental forage are fed to maintain high levels of milk production per cow. Although grazing is increasing in t...

Particulate organic matter (POM), an established soil quality indicator, is too costly for routine testing by analytical labs. Chemical oxidation of labile soil organic matter is less costly and may prove to be an equally effective indicator. The objectives of this study were to test the relationship between POM and chemically labile organic matter (CLOM) and to evaluate the effects of soil management on POM and CLOM. The study was conducted within a long‐term crop rotation × fertility treatment study in central Pennsylvania. Crop rotation sequences were continuous corn (Zea mays L.), corn–soybean [Glycine max (L.) Merr.], 4 yr of corn followed by 4 yr of alfalfa hay (Medicago sativa L.), and corn–oat (Avena sativa L.)–winter wheat (Triticum aestivum L.)–2 yr of red clover hay (Trifolium pratense L.). Fertilizer treatments were mineral fertilizer, N‐based liquid dairy manure, and P‐based liquid dairy manure. A significant linear relationship between POM‐C and CLOM‐C treatment means was observed (r2 = 0.74). Both POM‐C and CLOM‐C concentrations were greatest for manure‐based fertility treatments and for crop rotations receiving the most frequent applications of manure. Only CLOM‐C, however, distinguished between the N‐based and P‐based manure treatments. Further development of CLOM‐C as a soil quality indicator may yield a reliable, cost‐effective soil quality management tool.

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The magnitude, and spatial and temporal patterns of nutrient flow in the managed pathways of a farm are related to farm management decisions and interact with the biological processes of the farm. These descriptions of nutrient flow can be part of a nutrient management process that is consistent with the specifics of individual farm operations and particular farm performance goals. Nutrient flow in the managed pathways of a Pennsylvania dairy farm was measured at farm, field, and livestock unit boundaries using on‐farm equipment scales, farm records, and material sampling and analysis. Farm nutrient inputs of N, P, and K were twofold or more greater than outputs of these nutrients in the managed pathways. The temporal distribution of flows was closely related to the livestock activities on the farm. Manure storage capacity and crop developmental stage were significant factors influencing the timing of nutrient flows to and from the fields. Nutrient inputs and outputs in the managed flows at the boundary for the set of all fields were approximately equal except for the negative calculated crop available N balance. However, the range in balances for individual fields was large. Manure N and potential biological N fixation were not used efficiently on this farm due primarily to the volatilization of N from manure and the application of manure to alfalfa. Additions of nutrients to the farm in the managed flows decreased by 26, 60, and 43% for N, P, and K, respectively, in the 2nd yr of the study due primarily to less purchased animal feeds.

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