Data_Sheet_1_Unraveling feed and nutrient use efficiencies in grassland-based dairy farms.docx

Grassland-based dairy farms are important for the provisioning of milk and ecosystem services. However, the key factors and interactions that influence the feed use efficiency of grassland-based dairy farms in practice are not well known and understood, and as a consequence no well-targeted recommendations can be provided. This paper addresses the question ‘what are the main factors that determine the variations in calculated feed efficiency and N and P use efficiencies on dairy farms subjected to agri-environmental regulations’. Monitoring and modeling data from ~12000 grassland-based dairy farms in The Netherlands over a 4 year period (2017–2020), collected through the KringloopWijzer model, were analyzed and the data from 2020 were statistically analyzed in detail. Farms greatly differed in milk production intensity (range 25 Mg per ha per yr) and in the amount of purchased feed. The 5 and 95 percentile values of frequency distribution of the calculated annual mean feed efficiency at herd level were 0.9 and 1.3 kg milk per kg feed dry matter, respectively. Feed efficiency was statistically related to milk yield and number of young stock per cow, the share of concentrates and silage maize in the ration, and the net energy content of silage grass. At herd level, the 5 and 95 percentile values of the calculated annual mean N use efficiency increased with feed efficiency from 21 to 28%, and those of the annual mean P use efficiency from 32 to 40%. Contrary to expectations, mean surpluses of N and P at farm level remained more or less constant with feed efficiency and the intensity of milk production, but the amounts of purchased feed and manure export strongly increased with the intensity of milk production. The N and P surpluses and use efficiencies at farm level were sensitive to accounting for the externalization of feed production and manure utilization. The modeled ammonia and methane emissions per kg milk produced were relatively low on farms with high feed efficiency. In conclusion, feed use and N and P use efficiencies are key indicator for the profitability and environmental performance of dairy farms. Differences between farms in these key indicators were large, and these differences were related to a limited number of explanatory variables. Our study provides lessons for improving the profitability and environmental performance of grassland-based dairy farms.</p

Full set of crop parameters used in this study.

<p>Full set of crop parameters used in this study.</p

Results of six model experiments; effects of straw mulch and plastic film on wheat yield (A) and water use efficiency (B).

<p>Experiment E1: Planting at 50% of FC; Experiment E2: E1+organic mulch; Experiment E3: E1+plastic cover; Experiment E4: Planting at 70% of FC; Experiment E5: E4+organic mulch; Experiment E6: E4+plastic cover.</p

Activity of alkaline phosphatase of the autoclaved soil and the borax-borate buffer (control) with 50 mU external alkaline phosphatase as functions of sonication time.

<p>Activity of alkaline phosphatase of the autoclaved soil and the borax-borate buffer (control) with 50 mU external alkaline phosphatase as functions of sonication time.</p

Changes in soil water content in the upper 2 meter of the soil during the period of 1980–2010. A: water stored in the upper 2 meter during the fallow season, presented in positive percentage (in volume, v/v). B: water depletion in the upper 2 m during the growing season, presented in negative percentage (in volume, v/v).

<p>The soil water changes for fallow season were calculated as the soil water content of October deducted by that of June. Similarly, the soil water changes for growing season were calculated as the soil water content of June deducted by that of October in the previous year.</p

Activity of alkaline phosphatase of the field-moist soil as a function of sonication time. Data are means ± SD (<i>n</i> = 3).

<p>Activity of alkaline phosphatase of the field-moist soil as a function of sonication time. Data are means ± SD (<i>n</i>  =  3).</p

Relationships between observed yield and total rainfall (A), rainfall in fallow season (B), rainfall in growing season (C), measured ET (D), Transpiration (E) and WUE (F).

<p>The significant level is 0.028 for (A), 0.167 for (B), 0.027 for (C). For D, E and F, the significant level is all smaller than 0.01.</p

Temperature of 100 ml deionized water as a function of sonication power.

<p>Temperature of 100 ml deionized water as a function of sonication power.</p

Total bacteria number of field-moist soil as a function of sonication time.

<p>Total bacteria number of field-moist soil as a function of sonication time.</p

The AquaCrop Model simulations on yield (A) and soil water change (B).

<p>Diagonal lines represent 1∶1 lines.</p