Quantifying dairy farm nutrient fluxes and balances for improved assessment of environmental performance

Characterization of nitrogen, phosphorus, and potassium mass balances of dairy farms in New York State

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

This paper continues tbe analysis of nutrient management on a case study dairy farm in New York State. In Part I, it was found that 60 to 70% of the imported N and P were not accounted for in the exported milk, crops, and animals. The purpose of this paper is to present a process for accounting for the fate of the excess nutrients and to determine the extent to which they were contributing to air and water pollution from the farm. Environmental losses of N and net excess of P in different subsections of the farm were estimated. Losses of N from volatilization on the barn floor and in storage were estimated to be 16% of excreted N. As a partial check on these results, manure nutrient composition for lactating cows was analyzed at excretion, entering storage, and leaving storage. Soil leaching losses from the farm were calculated using the LEACHN model, and were 9% of total N inflows to the farm. Predicted nitrate N concentrations in the leachate were 10.6 ppm. Results from monitoring a stream originating from the farm gave an annual average of 14.4 ppm of nitrate N. About 80% of the total N inflows were accounted for as milk sold (25%), animals sold (2%), leaching losses (9%), and volatilization/denitrification losses (46%). Environmental losses accounted for 75% of the excess N. Projected scenarios for increased use of farm-produced forages, reduction in fertilizers, and increased feed conversion to milk resulted in only minor improvements in the nutrient imbalance on this farm.

States in the Chesapeake Bay watershed (CBW) are required to reduce nitrogen (N) and phosphorus (P) loads from agriculture to achieve water quality goals for 2025. Assessing nutrient mass balances (NMBs) on farms over multiple years allows for evaluation of trends in nutrient accumulation and potential losses in geographic regions. Between 2004 and 2013, 570 NMBs were conducted for 189 dairy farms in New York, including 91 farms (293 NMBs) in the Upper Susquehanna watershed (USW), headwaters of the CBW. The average NMBs per hectare and per megagram of milk were lower for farms in the USW than statewide. Data showed a decline in NMBs per hectare over 10 years that ranged from 29% to 42% (statewide) and from 29% to 51% (for the USW dairies), depending on the nutrient, while milk production remained constant in both regions. Reductions in NMBs resulted primarily from reductions in nutrient imports, particularly through feed management. These source reductions reflect increased efficiency of production and reduced risk of N and P loss to the CBW. Extrapolation of comparisons in NMBs between 2004 and 2013 suggest that dairies in the USW reduced total N and P imports by 30% and 20%, respectively, contributing to a 29% to 50% decrease in total N pool and 51% decrease in P pool. We conclude that USW dairy farms can deliver up to 49% of their 2013 N pool and up to 72% of their 2013 P pool at the edge of the farms (their NMB) and still meet the total maximum daily load (TMDL) for N and P set for 2025 for New York agriculture. This study illustrates that significant nutrient source reduction can be obtained by implementing nutrient conservation practices, such as precision feeding and fertilizer management, combined with annual assessment of whole farm balances. Such a reduction in nutrient imports onto farms results in a reduction of the pool of nutrients available for accumulation in the soil or direct loss to water bodies and the atmosphere.

<p>A whole farm nutrient mass balance (NMB) assessment gathers information on farm characteristics, nutrient imports and exports; provides indicators of farm production efficiency, potential environmental footprint; and helps identify opportunities for management improvements. Simplifying the data collection process facilitates wider NMB adoption. Our objectives were to: (1) integrate the NMB assessment into “Fields and Crops Manager”, an on-farm crop management program; (2) evaluate existing, on-farm, software packages for their ability to supply data for the assessment; and (3) document farmer response prior to and after conducting an NMB with the integrated record system. Software evaluated included the DRMS DHI-202 Herd Summary report, Centerpoint Accounting, PCDART and Quickbooks Accounting software, FeedWatch and TMR Tracker feeding systems, and Dairy Comp 305 herd management software. Six dairy farmers participated in the evaluation. The NMB results were presented and discussed in group meetings with each farmer. The records in the Fields and Crops Manager program and other software packages were not complete enough to allow for automated transfer of data into the NMB tool. Instead, the new NMB function within Fields and Crops Manager was used as a platform to enter, calculate, and store the NMB. Despite initial hesitation about participating, all six farmers concluded that (1) the NMB assessment was worth the data collection effort; and (2) meetings with farm advisors (crop planner, nutritionist) greatly improved the value of the NMB. The biggest obstacle to calculating NMBs can be overcome if purchases are recorded in the farm’s accounting software as invoices are entered.</p>

Nutrient loss and accumulation as well as associated environmental degradation have been a concern for animal agriculture for many decades. Federal and New York (NY) regulations apply to Concentrated Animal Feeding Operations and a comprehensive nutrient management plan (CNMP) is required for regulated farms. The whole farm nutrient mass balance (NMB) calculator was created to evaluate the impact of CNMPs and field or herd farm management changes on the whole farms’ nutrient use efficiency. This tool calculates the nitrogen (N), phosphorus (P) and potassium (K) imported onto and exported from the farm, and expresses the difference as N, P, and K balance per acre of cropland and per volume of milk produced. Farmers and their advisors can use the NMB calculator to compare their farm's nutrient balance to those of peers with similar milk production, to identify opportunities to increase nutrient use efficiency, and to monitor progress over time. The NMB calculator is used in a capstone course on whole farm nutrient management at Cornell University to communicate the challenges and opportunities in addressing the long-term sustainability of the dairy sector and to illustrate the potential for improvement over time. The objectives of this paper are to introduce the NMB calculator, outline the classroom NMB exercise, and describe both producer and agricultural student feedback on the usefulness of whole farm NMB assessment for reaching more sustainable balances.

Efficient management of N and P on dairy farms is critical for farm profitability and environmental stewardship. Annual farm-gate nutrient mass balance (NMB) assessments can be used to determine the nutrient-use efficiency of farms, set efficiency targets, and monitor the effect of management changes with minimal inputs required. In New York, feasible N and P balances have been developed as benchmarks for dairy farm NMB, alongside key performance indicators (KPI) that serve as predictors for high NMB. Here, 3 yr of NMB data from 47 farms were used to evaluate the main drivers of N and P balances and identify additional KPI. From the 141 farm records, 26% met both the feasible N balances per hectare and per megagram of milk produced. For P, 53% of the records met both benchmarks. Imports, rather than exports, drove NMB primarily by feed and fertilizer purchases, consistent with earlier findings. Linear regression analysis showed that a selection of KPI currently used, particularly animal density, nutrient-use efficiency, and the amount of home-grown feed, explained a large portion of variation in NMB. Heifer-to-cow ratio and the relative proportion of various forage crops may provide further insight into the drivers of feed and fertilizer imports and ultimately farm-gate NMB. This study provides avenues toward a better assessment of whole-farm nutrient management and means for farms to communicate progress to stakeholders and consumers.

Potential of life cycle assessment to support environmental decision making at commercial dairy farms

The calculation of whole-farm nutrient balance is an effective and simple method for estimating the potential nutrient loading from dairy farming into the environment. In Finland, however, the published results based on larger number of farms are still lacking. In this study whole-farm nitrogen (N) and phosphorus (P) balances on Finnish dairy farms were studied based on short-cut data for the year 2002. The survey was targeted to 1260 dairy farms, located all over Finland. Of the 386 replies received, 319 were used for subsequent statistical analyses. The association between selected farm variables and nutrient balance was studied using regression analysis and a sensitivity coefficient was calculated for each regression slope. The average (± standard deviation) whole-farm nutrient balance for N and P was 109 (±41.3) and 12 (±7.2) kg ha-1, respectively. The most responsive factors affecting the nutrient balances were total nutrient and fertilizer import per ha, followed by animal density, milk export per ha and concentrate import per ha. The results suggested that nutrient surpluses could be controlled more easily in combined crop and milk than in specialised milk production. It is concluded that nutrient surplus on Finnish dairy farms is markedly lower than that on areas with intensive production in central European countries. However, when nutrient balances were extrapolated to comparable production intensity as in central Europe, the level of the surpluses was equal.;

Guiding commercial pilot farms to bridge the gap between experimental and commercial dairy farms; the project ‘Cows & Opportunities’

Replacement heifers are key to the future milking herd and farm economic efficiency but are not always prioritised on dairy farms. Dairy enterprises are comprised of components which compete for limited resources; scarce information about calf performance and the associated losses and (potential) gains on farms can mean calves are prioritised less in management and investment decisions. The research reported in this paper explored the personal and contextual factors that influence calf management decisions on dairy farms. Forty in-depth, semi-structured interviews were conducted with dairy farmers (26 interviews) and farm advisors (14 interviews) who were recruited using purposive and “snowball” sampling. Interviews were recorded, transcribed, and thematically analysed. Six major themes were constructed from the interview data relating to: the perceived importance of youngstock management, the role and influence of calf rearers, calf performance monitoring, farmer engagement with information and advice, the quality of communication and advice, and veterinary involvement in calf rearing. Results indicated that although the wider dairy industry has promoted the importance of youngstock, calves often have not been fully integrated into the whole dairy farm system, nor culturally accepted as an integral part of the productive herd. Calves tended to be marginalised on farms, largely due to limited resources, lack of data monitoring, and their unrecognised potential, as well as social norms and scarcity of support structures impacting upon farm investment and management decisions. Many calf rearers were disappointed by the repetition and impractical nature of information in print media. Most farmers did not routinely consult their veterinarian about their calves, rather following a reactive treatment model even when a preventive herd health strategy was applied to the adult herd. Advisory structures often require a driven individual with calf-centric interest to prevent calves from being overlooked. Furthermore, advisory efforts often failed to motivate farmers to act on advice. These findings indicate the need for greater focus on how to achieve rearing targets by provision of technical and support structures to foster action toward improved calf wellbeing, and for the status of calves to be raised in line with their vital importance for the future dairy herd.

Sexed semen is one of the newest reproductive technologies available for dairy farmers and can fulfil their desire to produce a high percentage of female calves. The present study was designed to define the willingness of Indian dairy farmers to pay for sexed semen. Hence, 120 small holder dairy farmers and 90 commercial dairy farmers were randomly selected from Karnal and Yamunanagar districts in North-western Haryana, where there is a high proportion of crossbred dairy cattle. Willingness to pay for sexed semen was evaluated by a contingent valuation method and its determinants by an interval regression model. The majority of the small holder dairy farmers (81.67%) were willing to pay for sexed semen and they were ready to pay around INR 340 per sexed semen straw. Almost all (99%) of the commercial dairy farmers were willing to pay around INR 770 per sexed semen straw, i.e. more than double the value identified by small holder dairy farmers. Among all the predictors fitted in the interval regression model to explain the willingness to pay for sexed semen by the commercial dairy farmers, namely education level, herd size and attitude towards public extension systems, were positive and significant contributors. Our findings may help to identify what subsidy is required to promote sexed semen among dairy farmers, and as a consequence further improve breeding policies by introducing this new livestock production technology with the active participation of the dairy farmers.

Participatory farm management adaptations to reduce environmental impact on commercial pilot dairy farms in the Netherlands

A cross-sectional questionnaire-based study was conducted to assess milk producers' awareness of milk-borne zoonoses in selected smallholder and commercial dairy farms of Zimbabwe. The questionnaire was designed to obtain information on dairy breeds, milk production, dairy farmers' knowledge and awareness of zoonoses with particular emphasis on milk-borne zoonoses and farmers' behavioural practices that may lead to increased risk of milk-borne zoonoses transmission. A total of 119 dairy farmers were interviewed, and 41.5% were aware of milk-borne zoonoses with a significantly (P<0.01) higher percentage of commercial dairy farmers (65.0%) being aware compared to smallholder dairy farmers (36.7%). The behavioural practices of dairy farmers observed to increase the risk of milk-borne zoonoses transmission were; consumption of raw milk (68.1%), sale of raw milk to the local public (25.2%), lack of cooling facilities by smallholder farmers (98%), and no routine testing (84.9%) and medical check-ups (89.1%) for milk-borne zoonoses. General hygienic and disease control practices need to be integrated in the milk production process particularly at the smallholder level. Awareness, teaching and training programmes for smallholder dairy farmers can improve disease control in animals and reduce the public health risk of milk-borne zoonoses.

Stochastic uncertainty and sensitivities of nitrogen flows on dairy farms in The Netherlands