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| Title | Effects of Land Application of Manure on Groundwater at Two Dairies over the Sumas-Blaine Surficial Aquifer: Implications for Agronomic Rate Estimates | |||
| Month-Year Published | March 2002 | |||
| Online Availability |
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| Short Description |
The Washington State Department of Ecology (Ecology) monitored groundwater, soil pore liquid, and soil at two diary farms over the Sumas-Blaine Surficial Aquifer from 1997-2000. At the same time, Ecology compared manure and commercial fertilizer application with recommended agronomic rates. (Also see abstract below) | |||
| Publication Number | 02-03-007 | |||
| Author(s) | Carey, B. | |||
| Print Availability | ||||
| Number of pages | 148 pp. | |||
| Keywords | application, aquifer, groundwater, monitoring, soil, wells | |||
| Subject Waterbodies |
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| Abstract | Long Description |
The Washington State Department of Ecology (Ecology) monitored groundwater, soil pore liquid, and soil at two diary farms over the Sumas-Blaine Surficial Aquifer from 1997-2000. At the same time, Ecology compared manure and commercial fertilizer application with recommended agronomic rates. Fifteen monitoring wells and 12 soil pore-liquid samplers were installed within and upgradient of two spray fields. Monitoring wells and soil pore-liquid samplers were sampled monthly for ammonia-nitrogen, nitrate+nitrite-nitrogen (nitrate+nitrite-N), total nitrogen, chloride, total dissolved solids, total organic carbon, dissolved oxygen, temperature, pH, and specific conductivity. Composite soil samples were collected at each site in September to estimate residual nitrate and ammonia at the end of the growing season. Measured application rates exceeded agronomic rates by 10-600 lb/acre/year at Site 1, with the exception of one year when part of the site received close to the agronomic rate. At Site 2 the measured application rate ranged from below the agronomic rate to 140 lb/acre/year above the rate. The median groundwater nitrate+nitrite-N concentrations in downgradient wells at Site 1 (15.4 mg/L in the North Field and 19.6 mg/L in the South Field) were higher than the downgradient median at Site 2 (10.6 mg/L). The mean downgradient nitrate+nitrite-N concentration at Site 1, where nitrogen application exceeded the agronomic rate by a factor of 2 in most cases, was significantly greater than that upgradient at the 95% confidence level using the Student′s t-test. There was no difference between upgradient and downgradient nitrate+nitrite-N at Site 2, where the nitrogen application rate was close to the agronomic rate. The non-growing season mean nitrate+nitrite-N concentrations in groundwater were 24.3 mg/L at Site 1 and 9.8 mg/L at Site 2. The soil nitrate concentration at Site 1 (200-380 lb/acre) was up to three times higher than the very high level defined in Sullivan (1994) and was within the medium to high range at Site 2 (50-110 lb/acre). |
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