Abstract
Dairy farms are predominantly carbon sources, due to high livestock emissions from enteric fermentation and manure. Integrated crop–livestock systems (ICLSs) have the potential to offset these greenhouse gas (GHG) emissions, as recycling products within the farm boundaries is prioritized. Here, we quantify seasonal and annual greenhouse gas budgets of an ICLS dairy farm in Wisconsin USA using satellite remote sensing to estimate vegetation net primary productivity (NPP) and Intergovernmental Panel on Climate Change (IPCC) guidelines to calculate farm emissions. Remotely sensed annual vegetation NPP correlated well with farm harvest NPP (R2 = 0.9). As a whole, the farm was a large carbon sink, owing to natural vegetation carbon sinks and harvest products staying within the farm boundaries. Dairy cows accounted for 80% of all emissions as their feed intake dominated farm feed supply. Manure emissions (15%) were low because manure spreading was frequent throughout the year. In combination with soil conservation practices, ICLS farming provides a sustainable means of producing nutritionally valuable food while contributing to sequestration of atmospheric CO2. Here, we introduce a simple and cost-efficient way to quantify whole-farm GHG budgets, which can be used by farmers to understand their carbon footprint, and therefore may encourage management strategies to improve agricultural sustainability.
Highlights
Agricultural landscapes cover ~37% of the terrestrial surface on Earth
Annual rainfall amounted to approximately 1300 mm in 2018, which was ~400 mm higher compared to long-term records [64], with May and August receiving the largest amounts with >200 mm of rain
When expressed in area needed to offset farm emissions for ~750 dairy cattle, the farm would need to produce either corn, alfalfa, soybeans or wheat on 2.97, 2.46, 2.92 or 3.0 km2 of land, respectively, and the respective crop products would need to remain within the farm boundaries S(Tuastbailneab3i)li.tyF2o0r20n,a1t2u, xraFlOvRePgEeEtaRtRioEnVIeEiWther forests, shrub and grasslands would have to make up 2.8120, o2f.9281 wua2npkodmu2.2l82d.72(r9,~e20kq..9mu285i2rahetnoa2dopkff2em.sr7e29cto(kf~wam0r.)m22i5tnoehmsoaizfifspesseeitroot ncfoaosffr,wmrsee)steipnmeemsciistizissveisoeitonloyns.o,sAfrffeosfseraptr2eme0cm1twi8vi.siestlhiyo.onAnslfyfoaprrma2s0tw1u8ri.ethvoengelytaptiaosntuwreouvledgeretaqtuioirne
Summary
Agricultural landscapes cover ~37% of the terrestrial surface on Earth. Larger herd sizes are more efficient in terms of milk production [5], but they present challenges for achieving mass nutrient balances and offsetting emissions [10], as larger herds are concentrated on a smaller land base. Despite observed decreases in global agricultural land coverage [14], the sector is one of the largest contributors to nutrient runoff into aquatic systems [15,16,17,18,19], a major source for greenhouse gas release to the atmosphere [20,21] and a large factor in soil degradation [12]. Dairy, has been identified as a leading contributor to greenhouse gas emissions [22,23]
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