Diet Modification to Reduce Phosphorus Surpluses: A Mass Balance Approach

Abstract

Diet modification to reduce phosphorus (P) concentrations in manures has been developed in response to environmental concerns over P losses from animal agriculture to surface waters. We used USDA-NASS statistics on animal numbers and crop production to calculate county scale mass balances for manure P production, P removed in harvested portion of crops, and the potential effects of diet modification. Although spreading manure evenly over all crop acreage within a county is unlikely to occur, these calculations give a good indication as to the impact diet modification to reduce P can have at a regional or national scale. There was a high degree of regional variability in manure P surpluses (e.g., with the large crop acreages in the grain belt leading to large P offtake in crops preventing most P surpluses). In 89% of counties, there was a deficit of manure P relative to crop P removal; therefore there was a manure P surplus in 11% of counties. Diet modification decreased the percentage of states with a manure P surplus from 11 to 8%, a decrease of approximately 27%. Diet modification decreased the percentage of counties with the greatest surpluses of manure P (>30 kg ha(-1)) from 3% of all counties to 1%. Diet modification to decrease manure P is an important part of strategies to alleviate environmental concerns associated with surplus manure P in many areas, but additional strategies to deal with manure P surpluses are needed in some areas.

Feeding the Corn Belt: Opportunities for phosphorus recycling in U.S. agriculture

“…We find that Maguire et al's (2007) estimates of livestock feed modification (applied to the Mueller and Gronberg's (2013) P excretion rates used in our analysis) could reduce manure P available for recycling by 42% nationally. This would in turn reduce the total recyclable P sources available by 37%.…”

“…As such, policies and technologies ranging from food waste reduction and dietary change (Metson et al, 2012b), on-farm nutrient balancing (Lanyon et al, 2006), and maximizing nutrient-use efficiency based on crop choices (Jobbágy and Sala, 2014) should be considered in concert. We calculated two simple scenarios to illustrate how other prevailing P sustainability strategies discussed in the literature may interact with P recycling potential in the U.S. (Childers et al, 2011): (1) human diet modification with a reduction in P-intensive red meat production domestically (MacDonald et al, 2012a;Metson et al, 2012b); and (2) livestock feed modification to reduce manure P excretion by livestock (Maguire et al, 2007).…”

Phosphorus flows and balances of the European Union Member States

“…For example, in CP the PUE efficiency could be increased with (1) balanced and targeted fertilization by realigning the supply and demand of nutrients (Withers et al, 2015a), (2) implementing the 5R of plant nutrition: right timing, placement, type of fertilizer, application method and management (Schröder et al, 2011;Withers et al, 2014), and (3) improvement of crops in their P uptake and internal use efficiency by breeding and genetic modification (Gaxiola et al, 2011). In AP the PUE can be increased if the oversupply of P in feed diets is minimalized by simultaneously increasing the feed P availability, and thus the animal P uptake, and reducing the feed P content by biorefinery of feed ingredients and lower supplementation of inorganic P additives (Maguire et al, 2007). In FP the PUE can be enhanced by more efficient processing with fewer food losses and additional biorefinery steps (Sanders and van der Hoeven, 2008).…”

Greenhouse gas emissions when composting manure from cattle fed wheat dried distillers’ grains with solubles

“…This has led to increased availability and use of dried distillers' grains with solubles (DDGS) as a livestock feed (Berger and Good 2007;Klopfenstein et al 2007). With the nitrogen content in DDGS approximately two to three times that of unprocessed grain (Spiehs et al 2002;Widyaratne and Zijlstra 2007), adding DDGS to livestock diets could potentially change the manure pH, N form and content, and C/N ratio, given that these properties are influenced by diet (Hao et al 2005b;Velthof et al 2005;Yan et al 2006;Maguire et al 2007;Hao et al 2009). Hao et al (2009) reported increases in manure pH, NH 4 ?…”