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Runoff water quality after low‐disturbance manure application in an alfalfa–grass hay crop forage system
Author(s) -
Sherman Jessica F.,
Young Eric O.,
Coblentz Wayne K.,
Cavadini Jason
Publication year - 2020
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.1002/jeq2.20058
Subject(s) - surface runoff , manure , environmental science , agronomy , phosphorus , water quality , forage , zoology , nutrient , hay , chemistry , biology , ecology , organic chemistry
The impacts of low‐disturbance manure application (LDMA) on runoff water quality in hay crop forages are not well known. Our objective in this study was to determine surface runoff losses of total nitrogen (TN), ammonium N (NH 4 –N), nitrate N (NO 3 –N), total phosphorus (TP), dissolved reactive P (DRP), and suspended sediment from alfalfa ( Medicago sativa L.)–grass plots in central Wisconsin after surface broadcasting manure and LDMA compared with no application. Treatments were (a) surface banding (BAND), (b) surface banding with aeration (A/B), (c) shallow disk injection (INJECT), (d) surface broadcast (BCAST), and (e) a no‐manure control (CONT). Runoff events were generated ( n = 7) from replicated plots following a standardized rainfall simulation protocol. Although runoff was variable across plots and within treatments, mean runoff concentrations of TN ( P = .03), NH 4 –N ( P = .03), TP ( P = .001), and DRP ( P < .0001) were lower for incorporated (INJECT and A/B) vs. unincorporated (BCAST and BAND) treatments. INJECT had lower mean DRP concentration ( P = .02) than A/B and was similar to CONT and had lower cumulative TN ( P = .05), TP ( P = .07), and DRP ( P = .01) loads than A/B. Additionally, TP, TN, DRP, and NH 4 –N loads and concentrations were strongly related with soil surface manure coverage extent ( R 2 = 0.50–0.84; P < .0001), suggesting that manure was a main source of N and P losses. Although INJECT appeared to be the most effective in mitigating nutrient loss in surface runoff, more research is needed to determine LDMA impacts on farm economics, soil properties, and runoff water quality.