Nitrate leaching loss following application of organic manures to sandy soils in arable cropping. I. Effects of application time, manure type, overwinter crop cover and nitrification inhibition

Published source details Beckwith C.P., Cooper J., Smith K.A. & Shepherd M.A. (1998) Nitrate leaching loss following application of organic manures to sandy soils in arable cropping. I. Effects of application time, manure type, overwinter crop cover and nitrification inhibition. Soil Use and Management, 14, 123-130.
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This study is summarised as evidence for the following.

	Action	Category
	Change the timing of manure application Action Link
	Amend the soil with manures and agricultural composts Action Link
	Grow cover crops when the field is empty Action Link
	Amend the soil with formulated chemical compounds Action Link

Change the timing of manure application

A controlled, randomized, replicated site comparison study in 1990-1994 on sandy-loam in the UK (Beckwith et al. 1998) found greater nitrate losses following manure application in September-November (23.3 and 12.4 mg N/l lost at the two study sites, respectively), but applications in December or January were no different to the untreated control (< 0.5 mg N/l lost). Two manure treatments were tested at each site. Pig/cattle slurry and farmyard cattle manure were tested at a Shropshire site and poultry litter and farmyard manure were tested at a Nottinghamshire site.. Manures were applied at 200 kg N/ha monthly between September and January to overwinter fallow or onto winter rye Secale cereale. Both sites also had an untreated control. An extra treatment was included to test the nitrification inhibitor dicyandiamide, which was applied at 20 l/ha. All treatments were replicated three times at both sites. Plots were 12 x 4 m and 15 x 4 m at the Shropshire and Nottinghamshire sites respectively.
Amend the soil with manures and agricultural composts

A controlled, randomized, replicated study in 1990-1994 on sandy loam in the UK (Beckwith et al. 1998) found lower nitrate losses for farmyard manure (10 and 19 kg N/ha from sites A and B respectively) than for broiler litter (24 kg N/ha) or slurry (56 kg N/ha) treatments. Nitrate losses were greatest following manure application in September-November (23 and 12 mg N/l for sites A and B), but were tiny when applications were made in December or January (less than 0.5 mg N/l for both sites). There were two manure treatments at each site: site A (Shropshire) received pig/cattle slurry and cattle farmyard manure, and site B (Nottinghamshire) received broiler (poultry) litter and farmyard manure. Manures were applied at 200 kg N/ha monthly between September and January to overwinter fallow or onto winter rye Secale cereale. All treatments were replicated three times at both sites. Plots were 12 x 4 m and 15 x 4 m at sites A and B respectively.
Grow cover crops when the field is empty

A controlled, randomized, replicated site comparison study in 1990-1994 on a sandy loam in the UK (Beckwith et al. 1998) found 79% less nitrate leaching at site A and 42% less at site B when a winter cover crop was grown, compared with the fallow (104 and 50 kg N/ha for sites A and B respectively). There were two manure treatments at site A (Shropshire): pig/cattle slurry; cattle farmyard manure (FYM), and two manure treatments at site B (Nottinghamshire): broiler (poultry) litter; FYM. Manures were applied at 200 kg N/ha monthly between September and January to overwinter fallow or onto winter rye Secale cereale. An extra treatment was included to test the nitrification inhibitor DCD, which was applied at 20 l/ha. All treatments were replicated three times at both sites. Plots were 12 × 4 m and 15 × 4 m at sites A and B respectively. The total amount of nitrate lost through leaching and total soil mineral nitrogen was measured.
Amend the soil with formulated chemical compounds

A controlled, randomized, replicated site comparison study in 1990-1994 on a sandy loam in the UK (Beckwith et al. 1998) found that applying the nitrification inhibitor dicyandiamide with manure had little to no effect on reducing nitrate leaching (50 kg N/ha lost manure only, 42.5 kg N/ha lost manure with inhibitor). There were two manure treatments at each site: pig/cattle slurry and farmyard cattle manure in Shropshire and poultry litter and farmyard cattle manure in Nottinghamshire. Manures were applied monthly at 200 kg N/ha between September and January to overwinter fallow or directly onto winter rye Secale cereale. An extra treatment was included to test dicyandiamide, which was applied at 20 l/ha. All treatments were replicated three times at both sites. Plots were 12 x 4 m and 15 x 4 m in the Shropshire and Nottinghamshire sites, respectively. Total soil mineral nitrogen was measured.