Changes in nutrient mass balances over time and related drivers for 54 New York State dairy farms

Abstract

Whole-farm nutrient mass balances (NMB) can assist producers in evaluation and monitoring the nutrient status of dairy farms over time. Most of the previous studies that report NMB for dairy farms were conducted over 1 to 3 yr. In this study, annual N, P, and K mass balances were assessed on 54 dairy farms in New York State for 4 to 6 yr between 2005 and 2010 with the objectives to (1) document changes in NMB over time and drivers for change, and (2) identify nutrient use efficiency parameters that predicted the potential for improvement in NMB. The study farms varied in size (42 small, 12 medium and large) and management practices. Phosphorus, K, and 2 N balances (N1 without N2 fixation, and N2 including N2 fixation) were calculated. In general, farms with high initial NMB levels reduced them over time whereas farms with negative NMB tended to increase their NMB, demonstrating a tendency across all farms to move toward more optimal NMB levels over time. Sixty-three to 76% of farms (depending on the nutrient) reduced their NMB per hectare over the 4 to 6 yr, and 55 to 61% of these farms were able to do so while increasing milk production per cow. Across all farms, the overall reduction in NMB per hectare averaged -22kg of N/ha for N1 (29% reduction), -16kg of N/ha for N2 (15% reduction), -4kg of P/ha (36% reduction), and -10kg of K/ha (29% reduction). Change in feed imports was the most important driver for change in N and P balances across farms, whereas adjustments in both feed and fertilizer imports affected the K balances. Key predictors of potential areas for improvement in NMB over time include total nutrient imports, feed imports, animal density, percentage of farm-produced feed and nutrients, and feed nutrient use efficiency. Overall, this study highlights the opportunities of an adaptive management approach that includes NMB assessments to evaluate and monitor changes in nutrient use efficiency and cost-efficiency over time.

Proximal Sensing to Estimate Yield of Brown Midrib Forage Sorghum

“…In Part A, data were analyzed using the MIXED procedure in SAS (Littell et al, 1996;SAS Institute, 2009) to test the effect of orientation and height on the NDVI measurements, and the interaction between sensor settings and the location. In addition, regression analysis was used to model final yield using NDVI measurements as predictors.…”

“…Typical forage rotations on dairy farms in the state include 3 to 4 yr of corn followed by 3 to 4 yr of mixed alfalfa (Medicago sativa L.)/grass hay. Although corn silage yields have slowly increased over the past 50 yr (National Agricultural Statistics Service, 2016), recent work has shown that double cropping of corn silage with winter cereals such as cereal rye and triticale has the potential to increase overall yield beyond what could be obtained with corn silage only (Ketterings et al, 2015a(Ketterings et al, , 2015b, reducing the need for feed purchases and improving whole farm mass nutrient balances (Cela et al, 2014;Soberon et al, 2015).…”

Long-term trends of nitrogen and phosphorus mass balances on New York State dairy farms

“…In Soberon et al (2015), 6 key indicators were proposed for identifying the potential for improvement in NMB. Based on the 27-farm database, preliminary thresholds for 5 of these 6 key indicators were determined ( Figure 9).…”

“…Therefore, to truly evaluate the effect of management changes on NMB, long-term trends need to be analyzed. A study by Soberon et al (2015) analyzed NMB on 54 NY dairies over 4 to 6 yr and showed that 63 to 76% of the NMB decreased over time (depending on the nutrient), and >50% of the farms did so while increasing milk production per cow. Improvements in balances were primarily due to changes in feed imports.…”

“…Improvements in balances were primarily due to changes in feed imports. Soberon et al (2015) identified total nutrient imports, feed nutrient imports, animal density, percentage of homegrown feed, homegrown nutrients fed, and feed nutrient use efficiency as key indicators to identify areas for improvement in NMB. However, the study did not assess specific management changes made at the farm level.…”