Past and future phosphorus balances for agricultural cropland in New York State

Nitrogen balances for New York State: Implications for manure and fertilizer management

“…Several studies have shown improvements in statewide gross phosphorus (P) balances (manure P plus fertilizer P minus crop P removal) (Bundy and Sturgul 2001;Lanyon et al 2006;Mid-Atlantic Regional Water Program 2005;Swink et al 2009). For New York (NY), in 2002, crop P removal amounted to 21.1 million kg (46.5 million lb) versus 20.9 million kg (46.1 million lb) of P in manure and 12.7 million kg (28.1 million lb) in fertilizer P, resulting in a cropland P balance of +8.0 kg P ha -1 (7.2 lb P ac -1 ) (Swink et al 2009).…”

“…A net N balance, on the other hand, excludes N lost to the air through volatilization of ammonia from manure prior to application to the soil. The net N balance is also referred to as a "soil surface balance" by Oenema et al (2003) or a "cropland balance" when nutrient inputs and outputs from pasture or grazing lands are not included, as in the P balance studies by Lanyon et al (2006), Mid-Atlantic Regional Water Program (2005), and Swink et al (2009). The gross N balance approach is useful for an overall assessment of potential N loss to the environment, including the air, while the net (cropland) N balance approach allows for assessment of how closely cropland-available N inputs match crop removal N, the goal of best management practices (BMPs) for crop and dairy producers.…”

“…For New York (NY), in 2002, crop P removal amounted to 21.1 million kg (46.5 million lb) versus 20.9 million kg (46.1 million lb) of P in manure and 12.7 million kg (28.1 million lb) in fertilizer P, resulting in a cropland P balance of +8.0 kg P ha -1 (7.2 lb P ac -1 ) (Swink et al 2009). The statewide P balance for 2006 was estimated at +1.7 kg ha -1 (+1.5 lb ac -1 ), reflecting further reduction in P fertilizer sales and illustrating that a statewide balance for P is attainable.…”

“…Such nutrient balances can be used to summarize nutrient flows in the agricultural landscape; identify imbalances at various scales from farm to county, state, and national levels; indicate the impacts of nutrient management policy, recommendations, and extension education efforts; and assist in identification of areas where improvements in management are desirable or needed (Meisinger and Randall 1991;Oenema et al 2003;Swink et al 2009;Watson and Atkinson 1999).…”

Tradeoffs between production and perennial vegetation in dairy farming systems vary among counties in the northeastern U.S.

“…These numbers are derived from a simple P budget that does not account for mineral P fertilizers and does not consider other livestock industries (e.g., poultry or swine). In contrast, much more detailed statewide P budgets for New York (Swink et al, 2009) and Pennsylvania (Lanyon et al, 2006) reported P surpluses from agriculture of 8.0 kg P ha −1 and 14.1 kg P ha −1 in 2002, respectively. These higher values suggest that excess P and associated water pollution in the Northeast may stem more from overuse of mineral P fertilizers on cropland or manure from other livestock industries rather than from over population of dairy cattle at a county scale.…”