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A field experiment compared the effects of sheep, deer and catlle dung on pasture growth and soil nutrient status. Sheep and deer dung pellets degraded rapidly within three to eight weeks, while it was 12 months before all visible cattle diing had gone from the soil surface. The cattle dung initially reduced herbage yield owing to smothering. However, after 40 days, herbage around the edges of the dung patch responded positively to the dung and more dry matter was produced in this patch than in the control patch during the first 12 months. There was no measurable herbage response to sheep dung, but deer dung significantly increased herbage production. While the rate of nutrient application per unit area was similar for sheep and deer dung, the latter was more evenly spread within the patch area. Consequently, a greater percentage of pasture plants in the patch received nutrient additions from the deer dung and a measurable response was recorded. Twelve months after dung application, soil nitrate. pho.sphate and organic C were higher in dung patches than in the control patches. In cattle dung patches, this response was accompanied hy higher microbial biomass C levels, arylsulphatase and arylphosphatase activities. Some residual effect on organic C levels was still evident three years after cattle dung application.

Three field experiments were carried out to compare cattle and sheep urine patches in relation to (i) initial wetting pattern and volume of soil affected, (ii) soil solution ionic composition and (iii) the fate of lSN-labelled urine in the soil over the winter period. The distribution of Br-(used as a urine tracer) across the soil surface and down the profile was irregular in all the patches. The pasture area covered by Br-in the sheep patches was 0.04-0.06 m 2 and Br-was detected to a depth of 150 mm. Cattle patches were significantly larger covering a surface area of 0.38-0.42 m 2 and penetrating to a depth of 400 mm. The rapid downward movement of urine occurred through macropore flow but even so, over half of the applied Br-was detected in the 0-50 mm soil layer in both sheep and cattle patches. Due to the larger volume of urine added to the cattle patches (2000 mL for cattle and 200 mL for sheep) the effective application rate was about 5 L m -2 compared with 4 L m -2 for sheep. Concentrations of extractable mineral N and ionic concentrations in soil solution were higher in cattle than sheep patches particularly near the soil surface. In both sheep and cattle patches, urea was rapidly hydrolysed to NH +. and nitrification occurred between 14 and 29 days after urine application. Initially the major anions and cations in the soil solution were HCO 3, SO 4, CI-, NH +, Mg ++, K + and Na +, which were derived from the urine application. Ionic concentrations in the soil solution decreased appreciably over time due to plant uptake and possibly some leaching. As nitrification proceeded, NO 3 became the dominant anion in soil solution and the major accompanying cation was Ca ++. The fate of tSN-labelled urine-urea was followed during a 5 month period beginning in late autumn. Greater leaching losses of NO 3 occurred below cattle patches (equivalent to 60 kg N ha-~ below 300 mm and 37 kg N ha-1 below 600 mm) compared with sheep patches (10 kg N ha -1 below 300 mm and 1 kg N ha -1 below 600 mm). While 6% of the applied 15N was leached the amount of N leached was equivalent to 11% of the applied urine-N in cattle patches. This suggests that there was significant immobilsation-mineralisation turnover in urine patch soil with the release of mineral N from native soil organic matter. In both sheep and cattle patches 60% of the 15N was accounted for in plant uptake, remaining in the soil and leaching. About 40% of the applied N was therefore lost through gaseous emission.

New Zealand S U M M A R YChanges in soil solution composition and concentrations of exchangeable cations and mineral N in undisturbed cores of pasture soil were investigated in two experiments following applications of sheep urine to the cores. The major cations applied in the urine were K+ and Na+, and the major anions were HCO; and C1-. Addition of urine increased concentrations of exchangeable K+, Na+ and NH and measured ionic strength of the soil solution throughout the surface 15cm of soil, demonstrating that the urine moved through the core by macropore flow immediately following addition. Immediately following urine application the ionic strength in soil solution in the surface 2.5cm of soil increased from 4-6 mM to 24-41 mM.Hydrolysis of urine-urea was extremely rapid, and in less than 1 d high concentrations of NHI-N (i.e. 270-370 mg N kg-') had accumulated in the surface 0-2.5 cm of the urine patch, and soil pH had risen by over one unit. Nitrification then proceeded and, after approximately 15 d, NO; became the dominant form ofmineral N present. During nitrification, soil pH declined and the ionic strength of the soil solution increased substantially with NO; becoming the dominant anion present in solution. There were concomitant increases in the concentrations of Ca2+ and, to a lesser extent, Mg2+ in the soil solution as NO; concentrations increased. After approximately 30 d, concentrations of exchangeable NO; had risen to 250-330 mg N kg-', soil solution NO; concentrations had increased to about 80 mmol, dm-3, and ionic strength in the soil solution had increased to 130-140 mM. These results demonstrate the dominating effect of N transformations in causing large fluctuations in the pH, ionic composition and ionic strength of the soil solution in the urine patch. It was concluded that nutrient availability in the patch was affected directly by nutrient addition in urine, and also probably indirectly through the fluctuations in soil solution pH and ionic strength that occur.

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