Nitrate accumulation and movement under deficit irrigation in soil receiving cattle manure and commercial fertilizer

Nitrate leaching from agricultural soils can increase groundwater nitrate concentrations. The objectives of the study were to assess the accumulation and movement of nitrate in the soil profile over a 2-year period under deficit irrigation conditions following a one time application of N in cattle feedlot manure and commercial fertilizer to corn at rates to achieve yield goals expected under conditions of full irrigation. Cattle manure and ammonium nitrate were applied in 2002 at the University of Nebraska recommended rate (1M and 1F ; respectively) and cattle manure was applied at twice the recommended rate (2M) for N for the 2002 corn (Zea mays L.) crop. The recommended rate was based on expected yields under full irrigation. The manure N treatments were applied to percolation lysimeters and adjacent plots on a Cozad silt loam soil. Ammonium nitrate was applied only to the percolation lysimeters. Leachate from the lysimeters was extracted from a depth of 2.1 m and soil samples were collected from field plots in 0.3 m depth increments to 2.1 m on a periodic basis. Water available to the crop was sufficient to meet 89 and 79% of the potential crop ET in 2002 and 2003, respectively. When averaged over the manure N treatments, reduced ET resulted in grain yields that were approximately 2.1 and 2.7 Mg ha- 1 less than expected in 2002 and 2003. Under deficit water inputs there was leachate movement below the root zone. Leachate depths averaged over N treatments were, however, reduced by 15% (33 mm) in 2002 and 47% (102 mm) in 2003 compared with those reported under full irrigation. The average nitrate-N (NO3-N) concentrations in leachate were higher under the 2M treatment (41 mg L- 1) compared to the 1M treatment (17 mg L- 1). The average NO3-N concentrations in leachate from the 1F treatment (28 mg L- 1) was not different than the 1 or 2M treatments. There were trends for greater NO3-N mass losses in leachate averaged over all treatments in 2003 compared to 2002, indicating that NO3-N derived from the 2002 application leached to at least 2.4 m below the soil surface. There were no mass loss differences in leachate due to the 2001 crop in 2002. In 2003, mass of NO3-N in lysimeters cropped to soybean in 2001 were significantly higher (144 kg NO3-N ha 1) than the mass in lysimeters cropped to corn in 2001 (51 kg NO3-N ha-1). Nitrate-N mass increased in the 0.9- 2.1 m soil depth 12-13 months after manure N treatment applications. The 2M treatment had greater soil NO3-N mass than the 1M treatment for most sampling dates in the surface 0.9 m. This research shows that there can be significant nitrate losses under deficit irrigation when manure N is over applied. These losses are likely related to water initially stored below the root zone and preferential flow of water from irrigation and precipitation. Determining accurate yield expectations under deficit irrigation conditions, correct scheduling of irrigation, and the use current best management practices for N management can help minimize nitrate losses in leachate

Current knowledge on the environmental fate, potential impact, and management of growth-promoting steroids used in the US beef cattle industry

Growth promoting steroids and steroid-like compounds (GPSC) used by the US beef cattle industry are potential contaminants to water resources. Manure generated in concentrated animal feeding operations contains GPSCs that may enter the environment. Several studies have focused on off-site impacts of GPSC in aquatic life and suggest possible adverse impacts such as abnormal blood hormone levels, masculinization of females, feminization of males, altered sex ratios, intersexuality and reduced fertility. Other studies point to potential human health impacts including increased incidence of human cancers, sexual disorders, and decline in male: female ratio in human beings. However, the use of GPSCs in beef production provides benefits to both cattle producers (less time and cost to raise cattle) and consumers (lower meat prices) and to some extent on the environment. This review discusses major scientific findings and issues related to the use of GPSCs by the cattle industry, their environmental impacts, existing knowledge gaps and potential strategies to manage GPSC movement in the environment. We found that although there have been many studies, there is no consensus on the extent of the problem, and the effects in the environment. Current environmental regulations could be adapted to include GPSCs if necessary

Transport of steroid hormones in the vadose zone after land application of beef cattle manure

A variety of naturally occurring steroid hormones are regularly excreted by livestock, while additional steroid hormones have been used as growth promoters by the livestock industry. Depending on manure age and storage conditions, both groups of compounds are likely to be present during application to crops. Recent research suggests that some estrogens, androgens and progestagens in surface waters may originate from runoff after land application of livestock manure. Groundwater may also be impacted by livestock manure when used as a nutrient source to crops and may be indicated by excess nitrate in water. Few studies have been conducted to investigate the potential of steroid hormones contamination of groundwater. The objective of this study was to monitor leaching of steroid hormones and other compounds associated with livestock manure through the soil profile after land application of manure. The study was conducted near North Platte, Nebraska between April 2008 and July 2011 on a silt loam soil. Leachate was collected at the bottom of 2.4 meter deep monolithic percolation lysimeters to sample water leached beneath plots fertilized with manure. Soil samples were also collected from surrounding irrigated field plots. Treatments consisted of two manure handling procedures (stockpiling and composting) and a check receiving no manure application. Manure stored from a previous year’s cattle feeding pen study was sampled and analyzed for steroid hormone content. Manure was applied to the lysimeters and adjacent plot areas in April 2008 at a rate satisfying the nitrogen requirements of winter wheat planted in the fall of 2007 and 2008 followed by soybeans planted in the spring of 2010 and 2011. Leachate from the lysimeters and soil samples (down to 2.4 meter depth) from surrounding areas were collected periodically during the study. Laboratory analyses of manure, soil, and leachate samples used liquid chromatography tandem mass spectrometry to identify 17 steroid hormones and metabolites. Progesterone, estrone, beta-zearalenol and 4-androstenedione were detected at varying concentrations in both composted (1.6-8.4 nanograms per gram) and stockpiled (3.7-11.4 nanograms per gram) manure. Steroid hormones and related compounds were detected in only 5 percent of the leachate samples. The greatest detected concentration was 20 nanograms per liter of natural progesterone in a leachate sample from a lysimeter treated with stockpiled manure. Steroid hormones or metabolites were detected in 10 percent of the soil samples. Seventy four percent of the detections in the soil samples were in the top half (top 1.2 meter) of the sampled soil depth. 17beta-estradiol was detected the most in the soil samples (4 percent) with a maximum concentration of 4.3 nanograms per gram in a plot treated with composted manure. No synthetic steroids were detected in any of the soil or leachate samples. The low detection of steroid hormones in the soil and leachate samples suggests that, while some hormones may move through the soil, most are readily degraded or adsorbed after manure application. Additional research is required to more clearly identify the mechanisms that control the environmental fate and transport of steroid hormones through the soil

Current knowledge on the environmental fate, potential impact, and management of growth-promoting steroids used in the US beef cattle industry

Growth promoting steroids and steroid-like compounds (GPSC) used by the US beef cattle industry are potential contaminants to water resources. Manure generated in concentrated animal feeding operations contains GPSCs that may enter the environment. Several studies have focused on off-site impacts of GPSC in aquatic life and suggest possible adverse impacts such as abnormal blood hormone levels, masculinization of females, feminization of males, altered sex ratios, intersexuality and reduced fertility. Other studies point to potential human health impacts including increased incidence of human cancers, sexual disorders, and decline in male: female ratio in human beings. However, the use of GPSCs in beef production provides benefits to both cattle producers (less time and cost to raise cattle) and consumers (lower meat prices) and to some extent on the environment. This review discusses major scientific findings and issues related to the use of GPSCs by the cattle industry, their environmental impacts, existing knowledge gaps and potential strategies to manage GPSC movement in the environment. We found that although there have been many studies, there is no consensus on the extent of the problem, and the effects in the environment. Current environmental regulations could be adapted to include GPSCs if necessary

Transport of steroid hormones in the vadose zone after land application of beef cattle manure

A variety of naturally occurring steroid hormones are regularly excreted by livestock, while additional steroid hormones have been used as growth promoters by the livestock industry. Depending on manure age and storage conditions, both groups of compounds are likely to be present during application to crops. Recent research suggests that some estrogens, androgens and progestagens in surface waters may originate from runoff after land application of livestock manure. Groundwater may also be impacted by livestock manure when used as a nutrient source to crops and may be indicated by excess nitrate in water. Few studies have been conducted to investigate the potential of steroid hormones contamination of groundwater. The objective of this study was to monitor leaching of steroid hormones and other compounds associated with livestock manure through the soil profile after land application of manure. The study was conducted near North Platte, Nebraska between April 2008 and July 2011 on a silt loam soil. Leachate was collected at the bottom of 2.4 meter deep monolithic percolation lysimeters to sample water leached beneath plots fertilized with manure. Soil samples were also collected from surrounding irrigated field plots. Treatments consisted of two manure handling procedures (stockpiling and composting) and a check receiving no manure application. Manure stored from a previous year’s cattle feeding pen study was sampled and analyzed for steroid hormone content. Manure was applied to the lysimeters and adjacent plot areas in April 2008 at a rate satisfying the nitrogen requirements of winter wheat planted in the fall of 2007 and 2008 followed by soybeans planted in the spring of 2010 and 2011. Leachate from the lysimeters and soil samples (down to 2.4 meter depth) from surrounding areas were collected periodically during the study. Laboratory analyses of manure, soil, and leachate samples used liquid chromatography tandem mass spectrometry to identify 17 steroid hormones and metabolites. Progesterone, estrone, beta-zearalenol and 4-androstenedione were detected at varying concentrations in both composted (1.6-8.4 nanograms per gram) and stockpiled (3.7-11.4 nanograms per gram) manure. Steroid hormones and related compounds were detected in only 5 percent of the leachate samples. The greatest detected concentration was 20 nanograms per liter of natural progesterone in a leachate sample from a lysimeter treated with stockpiled manure. Steroid hormones or metabolites were detected in 10 percent of the soil samples. Seventy four percent of the detections in the soil samples were in the top half (top 1.2 meter) of the sampled soil depth. 17beta-estradiol was detected the most in the soil samples (4 percent) with a maximum concentration of 4.3 nanograms per gram in a plot treated with composted manure. No synthetic steroids were detected in any of the soil or leachate samples. The low detection of steroid hormones in the soil and leachate samples suggests that, while some hormones may move through the soil, most are readily degraded or adsorbed after manure application. Additional research is required to more clearly identify the mechanisms that control the environmental fate and transport of steroid hormones through the soil

Nitrate accumulation and movement under deficit irrigation in soil receiving cattle manure and commercial fertilizer

Nitrate leaching from agricultural soils can increase groundwater nitrate concentrations. The objectives of the study were to assess the accumulation and movement of nitrate in the soil profile over a 2-year period under def¬icit irrigation conditions following a one time application of N in cattle feedlot manure and commercial fertilizer to corn at rates to achieve yield goals expected under conditions of full irrigation. Cattle manure and ammonium nitrate were applied in 2002 at the University of Nebraska recommended rate (1M and 1F, respectively) and cat¬tle manure was applied at twice the recommended rate (2M) for N for the 2002 corn (Zea mays L.) crop. The rec¬ommended rate was based on expected yields under full irrigation. The manure N treatments were applied to percolation lysimeters and adjacent plots on a Cozad silt loam soil. Ammonium nitrate was applied only to the percolation lysimeters. Leachate from the lysimeters was extracted from a depth of 2.1 m and soil samples were collected from field plots in 0.3 m depth increments to 2.1 m on a periodic basis. Water available to the crop was sufficient to meet 89 and 79% of the potential crop ET in 2002 and 2003, respectively. When averaged over the ma¬nure N treatments, reduced ET resulted in grain yields that were approximately 2.1 and 2.7 Mg ha-1 less than ex¬pected in 2002 and 2003. Under deficit water inputs there was leachate movement below the root zone. Leachate depths averaged over N treatments were, however, reduced by 15% (33 mm) in 2002 and 47% (102 mm) in 2003 compared with those reported under full irrigation. The average nitrate-N (NO3−-N) concentrations in leachate were higher under the 2M treatment (41 mg L-1) compared to the 1M treatment (17 mg L-1). The average NO3−-N concentrations in leachate from the 1F treatment (28 mg L-1) was not different than the 1 or 2M treatments. There were trends for greater NO3−-N mass losses in leachate averaged over all treatments in 2003 compared to 2002, indicating that NO3−-N derived from the 2002 application leached to at least 2.4 m below the soil surface. There were no mass loss differences in leachate due to the 2001 crop in 2002. In 2003, mass of NO3--N in lysimeters cropped to soybean in 2001 were significantly higher (144 kg NO3--N ha-1) than the mass in lysimeters cropped to corn in 2001 (51 kg NO3--N ha-1). Nitrate-N mass increased in the 0.9–2.1 m soil depth 12–13 months after ma-nure N treatment applications. The 2M treatment had greater soil NO3−-N mass than the 1M treatment for most sampling dates in the surface 0.9 m. This research shows that there can be significant nitrate losses under deficit irrigation when manure N is over applied. These losses are likely related to water initially stored below the root zone and preferential flow of water from irrigation and precipitation. Determining accurate yield expectations under deficit irrigation conditions, correct scheduling of irrigation, and the use current best management prac¬tices for N management can help minimize nitrate losses in leachate