Spatial variation of soil test phosphorus in a long‐term grazed experimental grassland field

The spatial variation of soil test P (STP) in grassland soils is becoming important because of the use of STP as a basis for policies such as the recently EU‐introduced Nitrate Directive. This research investigates the spatial variation of soil P in grazed grassland plots with a long‐term (38 y) experiment. A total of 326 soil samples (including 14 samples from an adjacent grass‐wood buffer zone) were collected based on a 10 × 10 m² grid system. The samples were measured for STP and other nutrients. The results were analyzed using conventional statistics, geostatistics, and a geographic information system (GIS). Soil test P concentrations followed a lognormal distribution, with a median of 5.30 mg L^–1 and a geometric mean of 5.35 mg L^–1. Statistically significant (p < 0.01) positive correlation between STP and pH was found. Spatial clusters and spatial outliers were detected using the local Moran's I index (a local indicator of spatial association) and were mapped using GIS. An obvious low‐value spatial‐cluster area was observed on the plots that received zero‐P fertilizer application from 1968 to 1998 and a large high‐value spatial‐cluster area was found on the relatively high‐P fertilizer application plots (15 kg ha^–1 y^–1). The local Moran's I index was also effective in detecting spatial outliers, especially at locations close to spatial‐cluster areas. To obtain a reliable and stable spatial structure, semivariogram of soil‐P data was produced after elimination of spatial outliers. A spherical model with a nugget effect was chosen to fit the experimental semivariogram. The spatial‐distribution map of soil P was produced using the kriging interpolation method. The interpolated distribution map was dominated by medium STP values, ranging from 3 mg to 8 mg L^–1. An evidently low‐P‐value area was present in the upper side of the study area, as zero or short‐term P fertilizer was applied on the plots. Meanwhile, high‐P‐value area was located mainly on the plots receiving 15 kg P ha^–1 y^–1 (for 38 y) as these plots accumulated excess P after a long‐term P‐fertilizer spreading. The high‐ or low‐value patterns were in line with the spatial clusters. Geostatistics, combined with GIS and the local spatial autocorrelation index, provides a useful tool for analyzing the spatial variation in soil nutrients.     

Variation of soil P and other nutrients in a long-term grazed grassland P experiment field

Field-scale variation of soil phosphorus (P) information is very important for P fertilizer application and its soil sampling design in grassland. A total of 108 soil samples were collected from a long-term (41 years) grazed grassland P experiment field at Teagasc, Johnstown Castle, Wexford, Ireland, in March 2009. There were six P treatments (P0-0, P0-30, P15-15, P15-5, P30-30, and P30-0) since 1968, with changes since 1999. Each treatment had 6 replicate plots (a total of 36 plots, 3 soil samples per plot). The samples were analyzed for available (Morgan’s) P, potassium (K), magnesium (Mg), lime requirement (LR), and pH. The highest mean available P concentration was found in the P30-30 (30 kg P ha^?1 pre- and post-1998) plots, and the lowest mean available P concentration was found in the P0-0 (no P fertilizer since 1968) plots. Significant differences of mean P, Mg, LR, and pH values in different treatments were observed. There was a positive proportional effect for both the 36 plots and the 6 treatments for the P data: the local standard deviation increased with the increase of local mean. The proportional effect should be considered in order to optimize sampling design. Fewer samples can reflect soil P status in fields with low soil P levels, while more attention should be paid to the fields with high P levels in order to reduce environmental consequences of uniform applications.     

Impact of grazed grassland management on total N accumulation in soil receiving different levels of N inputs

Nitrogen balances and total N and C accumulation in soil were studied in reseeded grazed grassland swards receiving different fertilizer N inputs (100–500 kg N ha^?1 year^?1) from March 1989 to February 1999, at an experimental site in Northern Ireland. Soil N and C accumulated linearly at rates of 102–152 kg N ha^?1 year^?1 and 1125–1454 kg C ha^?1 year^?1, respectively, in the top 15 cm soil during the 10 year period. Fertilizer N had a highly significant effect on the rate of N and C accumulation. In the sward receiving 500 kg fertilizer N ha^?1 year^?1 the input (wet deposition + fertilizer N applied) minus output (drainflow + animal product) averaged 417 kg N ha^?1 year^?1. Total N accumulation in the top 15 cm of soil was 152 kg N ha^?1 year^?1. The predicted range in NH₃ emission from this sward was 36–95 kg N ha^?1 year^?1. Evidence suggested that the remaining large imbalance was either caused by denitrification and/or other unknown loss processes. In the sward receiving 100 kg fertilizer N ha^?1 year^?1, it was apparent that N accumulation in the top 15 cm soil was greater than the input minus output balance, even before allowing for gaseous emissions. This suggested that there was an additional input source, possibly resulting from a redistribution of N from lower down the soil profile. This is an important factor to take into account in constructing N balances, as not all the N accumulating in the top 15 cm soil may be directly caused by N input. N redistribution within the soil profile would exacerbate the N deficit in budget studies.     

Phosphorus‐31–nuclear magnetic–resonance spectroscopy to trace organic dung phosphorus in a temperate grassland soil

Cattle dung contributes to hot‐spot inputs of nutrients to grassland systems, but not much is known about its organic P (P_o) composition and fate in the grassland soils. We used ³¹Phosphorus (P)–Nuclear Magnetic–Resonance (NMR) spectroscopy of alkaline soil extracts to examine potentials for tracing of different functional P_o forms into a temperate grassland soil amended with dung. The proportion of monoester, DNA‐diester, and phospholipid+teichoic acid P were comparable in dung extracts, but the soil was dominated by monoester P. The temporal trends in the DNA‐diester P–to–monoester P (D_DNAM) and diester P–to–monoester P (DM) ratio of dung, native soil, and soil amended with dung were monitored in the 70 d field experiment. The D_DNAM and DM ratio in the dung‐amended soil (0–1 and 1–5 cm depth) were always intermediate between the dung and (unamended) control soil. Clearly, extracted soil P was a mixture of incorporated dung‐derived P and native soil P. The dung‐P contribution in the 0–1 cm samples peaked at 47% of the total extracted P at day 70 and at 15% after 42 d in the 1–5 cm soil depth (based on the DM ratio). The proportions of dung‐derived P and C in the soil were positively correlated with: 1) topsoil, using the D_DNAM ratio (r² = 0.975), and 2) top‐ and subsoil, using the DM ratio (r² = 0.656). We concluded that our D_DNAM and DM‐P ratios approach (obtained from solution‐³¹P NMR) did trace successfully the short‐term dynamics and fate of dung P_o in soil. It indicated that dung‐derived P_o varied as rapidly in soil as the dung‐derived C.     

Crop nitrogen recovery and soil nitrogen dynamics in a 10‐year field experiment with biowaste compost

When fertilizing with compost, the fate of the nitrogen applied via compost (mineralization, plant uptake, leaching, soil accumulation) is relevant both from a plant‐production and an environmental point of view. In a 10‐year crop‐rotation field experiment with biowaste‐compost application rates of 9, 16, and 23 t ha^–1 y^–1 (f. m.), the N recovery by crops was 7%, 4%, and 3% of the total N applied via compost. Due to the high inherent fertility of the site, N recovery from mineral fertilizer was also low. In the minerally fertilized treatments, which received 25, 40, and 56 kg N ha^–1 y^–1 on average, N recovery from mineral fertilizer was 15%, 13%, and 11%, respectively. Although total N loads in the compost treatments were much higher than the N loads applied with mineral fertilizer (89–225 kg N_tot ha^–1 y^–1 vs. 25–56 kg N_tot ha^–1 y^–1; both on a 10‐year mean) and the N recovery was lower than in the treatments receiving mineral N fertilizer, soil NO ‐N contents measured three times a year (spring, post‐harvest, autumn) showed no higher increase through compost fertilization than through mineral fertilization at the rates applied in the experiment. Soil contents of N_org and C_org in the plowed layer (0–30 cm depth) increased significantly with compost fertilization, while with mineral fertilization, N_org contents were not significantly higher. Taking into account the decrease in soil N_org contents in the unfertilized control during the 10 years of the experiment, 16 t compost (f. m.) ha^–1 y^–1 just sufficed to keep the N_org content of the soil at the initial level.     

Effects of long-term phosphorus fertilizer inputs and seasonal conditions on organic soil phosphorus cycling under grazed pasture

Soil microbes and phosphatase enzymes play a critical role in organic soil phosphorus (P) cycling. However, how long-term P inputs influence microbial P transformations and phosphatase enzyme activity under grazed pastures remains unclear. We collected top-soil (0–75 mm) from a grazed pasture receiving contrasting P inputs (control, 188 kg ha⁻¹ year⁻¹ of single super phosphate [SSP], and 376 kg ha⁻¹ year⁻¹ of SSP) for more than 65 years. Olsen P, microbial biomass P, and acid and alkaline phosphatase enzyme activities were measured regularly over a 2-year period. Pasture dry matter and soil chemical properties were also investigated. Results showed that long-term P inputs significantly increased pasture dry matter, total N, and the concentrations of ${\mathrm{NO}}_3^{–}$–N but significantly decreased soil pH and the concentrations of ${\mathrm{NH}}_4^{+}$–N. Total C was not affected by P fertilization. Although Olsen P significantly increased with increasing long-term P inputs, microbial biomass P was similar under P fertilized treatments. Long-term P inputs decreased acid phosphatase activity but increased alkaline phosphatase activity. Microbial biomass P was similar across seasons in the control but decreased in spring and autumn while increased in summer and winter under P fertilized treatments. Acid and alkaline phosphatase activities were significantly affected by season and followed similar seasonal trends being maximum in summer and minimum in winter regardless of P treatment. Correlation and principal component analysis revealed that acid and alkaline phosphatase activities were significantly positively correlated with soil temperature and significantly negatively correlated with soil moisture. In contrast, Olsen P and microbial biomass P were weakly correlated with environmental conditions. The findings of this study highlight the intertwined relationship between organic P cycling and the availability of C and N in soil systems and the need to integrate both soil moisture and temperature in models predicting organic P mineralization, especially in the context of global climate change.     

Effects of long-term grassland management on the chemical nature and bioavailability of soil phosphorus

Relationships between the relative solubility of soil phosphorus (P) and short-term plant P uptake were investigated using soils obtained from a field trial that had been maintained under contrasting mowing regimen (no mowing, mowing with clippings left, mowing with clippings removed) for 15?years. In a glasshouse pot experiment, P uptake by red clover and Italian ryegrass was found to be 40% lower for the clippings removed treatment compared with the no mowing treatment, which was consistent with the fact that concentrations of readily extracted inorganic P were 42% lower in the clippings removed treatment soil. However, P uptake was 51–54% higher for the clippings left treatment soil compared with no mowing, despite the fact that levels of readily extracted soil inorganic P were similar in both treatments. This indicated that biological and biochemical processes associated with enhanced mineralisation of organic P and turnover of P through the microbial biomass made a greater contribution to increased plant P uptake in the clippings left soil compared with the other treatments. These findings highlight the importance of soil biological processes in determining the P nutrition and productivity of managed grasslands.     

Time‐dependent,anisotropic pore structure and soil strength in a 10‐year period after intensive tractor wheeling under conservation and conventional tillage

Any soil deformation induced by agricultural machinery is transmitted three‐dimensionally and the “kneading effect” of tractor wheeling further rearranges soil particles and aggregates anisotropically. In this work, we investigated how heterogeneous soil structure remained 10 y after a complete wheeling of fields in 1995 with a single pass of 2 × 2.5 Mg and of 6 × 5 Mg on a silty loam Luvisol derived from loess. Control plots received no tractor wheeling. We also analyzed how soil physical properties responded to the tractor wheeling under two management systems: continuous conservation tillage (chisel plow = CS) with mulch cover and conventional tillage (plowing to 25 cm depth annually = CT). We compared three sampling dates: done before wheeling in 1995, after wheeling in 1995, and in 2004. Results showed that applying tractor wheeling in 1995 not only reduced total soil‐pore volume but also increased soil strength as expressed by precompression stress. The reduction of total pore volume at 30 cm depth was more pronounced in CS than in CT. After 10 y of continuous use of the two tillage systems, the precompression stress of the wheeled soils was greater in the vertical direction than in the horizontal direction. This anisotropy of soil strength and its load dependency were also more pronounced in CS than in CT. The effect of wheeling on the fluxes of gas and water was covered up by the effects of biochannels, causing a prevailing vertical passage. From this study, we conclude that heavy, agricultural machinery causes soil degradation, which is more evident in CS than in CT.     

Spatial distribution of soil nutrient at depth in black soil of Northeast China: a case study of soil available phosphorus and total phosphorus

Purpose

The spatial variability of soil available phosphorus (AP) and total phosphorus (TP) influences crop yield and the environment. The paper aims to identify the spatial heterogeneity of P (AP and TP) and clarify the main driving mechanisms in a Mollisol watershed of Northeast China.

Materials and methods

Both geostatistical and traditional analysis were used to describe the spatial distribution of P at different depths. P in cultivated fields on the upper slopes was compared with secondary forest areas on the lower slopes within the same watershed.

Results and discussion

The horizontal distribution of P was found to be primarily influenced by structural factors (58–95 %). TP was high at both the summit and the bottom of slopes at all depths, being especially high at the watershed outlet due to erosion on the back slope and deposition at the base. AP was higher on south-facing slopes than on north-facing slopes and typically decreased from the summit to the base of south-facing slopes at the 0–40-cm depths, mainly due to solar radiation, soil loss, and water loss. The vertical distribution of TP typically decreased with increasing depths in farmland but did not show systematic variation in the forest profiles. AP was lower in the middle of the 0–60-cm soil profiles in the farmland, reflecting the influence of fertilization, infiltration, and crop absorption. AP in the 30–60-cm and TP in the 20–60-cm layers were lower in farmland than in the secondary forest, and only 2 % of the area showed a risk of P loss through ground flow and infiltration in the 0–20-cm layer.

Conclusions

The horizontal distribution of P in the 0–60-cm layers was mainly influenced by soil and water loss, deposition, and hydrothermal dynamics, while the vertical distribution of P, especially AP, was more affected by fertilization, infiltration, organic matter, and crop absorption. Secondary forestland that had been converted from farmland was found to effectively hold P, especially in deep soil layers, as the loss of P dissolved in water is not a primary process.     

A single drought event of 100‐year recurrence enhances subsequent carbon uptake and changes carbon allocation in experimental grassland communities

Evidence suggests that the expected increase in frequency and magnitude of extreme weather events during climate change will alter plant productivity. Therefore, extreme weather events might also be capable of changing C sequestration and allocation. Here, experimental grassland communities of two species compositions, differing in their diversity, were exposed either to a simulated single drought or to a heavy‐rainfall event. The magnitude of these manipulations imitated the local 100‐year weather extreme according to extreme‐value statistics. Effects on Net Ecosystem CO₂ Exchange (NEE in µmol m^–2 s^–1) as well as aboveground biomass production and leaf‐area index (LAI) were recorded from prior to the manipulations until two months after the manipulations ended. Initial light utilization efficiency and maximum NEE increased after the drought. No change in the respiration was detected and maximum uptake capacity (GPP_max) was 15% higher for the drought‐manipulated plots compared to controls, which indicates an enhanced CO₂ uptake into the systems. The level of diversity was also found to alter the light‐response curves, increasing respiration and maximum NEE to a higher degree than drought in the more diverse compared to the less diverse community. This resulted in an increase of GPP_max by 55%. No significant interactions between species composition and weather manipulations were detected. Interestingly, aboveground biomass production was not significantly affected by weather manipulations, even though LAI increased due to drought. This increase was caused by a decrease in the ratio between reproductive and vegetative growth. The heavy‐rainfall manipulation resulted in no significant effects. Our data suggest that C sequestration can be enhanced by a single weather event. However the importance, long‐term duration, and thresholds or turning points of such effects need to be investigated further as intensification of weather extremes is currently emerging as one of the most important facets of climate change.     

Relationship of soil phosphorus with uranium in grassland mineral soils in Ireland using soils from a long‐term phosphorus experiment and a National Soil Database

Phosphorus fertilizer contains contaminants that may increase the content in the soil and in plants. The relationship between soil P and soil uranium (U) was investigated to determine potential effects of P‐fertilizer use. This study is based on a long‐term experiment (38 years with 0, 15, and 30 kg fertilizer P ha^–1 y^–1) for beef production on grassland at Teagasc, Johnstown Castle, Wexford, Ireland and also on soils from a National Soil Database (NSD). The NSD soils were taken at fixed locations on a predetermined grid system at the density of one sample every 50 km². Of the 1310 samples in the NSD, the 760 grassland mineral soils were selected for this study. The aim was to determine to what extent P fertilizer increases the content of U in the soil. The results showed that there was a small but significant increase in soil U in the high‐P treatments, which contained high levels of soil P, in the long‐term field experiment. The results from the NSD showed that there was not a significant relationship between extractable (Morgan's) soil test P (STP) and U. It is concluded that the use of chemical P fertilizer at normal rates used in agriculture in Ireland is not a major threat to U content of soil based on the results of this study. There was a significant relationship between total P and STP, in the NSD, with the latter making up approx. 1% of the former. Soil available P increased with soil pH, probably reflecting the use of chemical P fertilizer and lime on agricultural soils.     

Effect of air‐drying on phosphorus fractions in clay soil

Despite the publication of a number of papers dealing with the effect of drying on the soil labile P pool, less attention has been paid to the possible drying‐evoked changes in the more stable P pools. We applied Hedley's sequential fractionation procedure that aims at quantifying soil P reserves according to their decreasing plant availability to examine the effects of drying on soil P fractions in clayey soil samples of different cultivation history. To further investigate the contribution of organic matter disruption to the solubility of soil P, the P extracted in each fractionation step was divided into two size classes by filtering the suspension through a 0.2 μm membrane filter. There were no air‐drying‐induced changes in the total amount of P extracted in each fractionation step. However, air‐drying changed the distribution of water‐extractable P in size fractions; increase in the small‐sized P took place at the expense of large‐sized P. Air‐drying increased also small‐sized molybdate‐unreactive P (MUP) in the NaOH fraction giving evidence that drying‐induced alterations take place also in less labile P forms. The results revealed that air‐drying alters the extractability and distribution of P in various pools rather than the total amount of extracted P and that a large proportion of H₂O‐ and NaOH‐extractable large‐sized MUP may remain undetected if only filtered samples are analyzed.     

Effects of different quality plant residues on soil carbon accumulation and aggregate formation in a tropical sandy soil in Northeast Thailand as revealed by a 10‐year field experiment

Particulate organic matter (POM) plays important role in soil organic carbon (SOC) retention and soil aggregation. This paper assesses how quality (chemical composition) of four different‐quality organic residues applied annually to a tropical sandy loam soil for 10 years has affected POM pools and the development of soil aggregates. Water‐stable aggregate size distribution (>2, 0·25–2, 0·106–0·25 mm) was determined through wet sieving. Density fractionation was employed to determine POM (light—LF, and heavy—HF fractions, 0·05–1 mm). Tamarind leaf litter showed the highest SOC (<1 mm) accumulation, while rice straw showed the lowest. LF‐C contents had positive correlations with high contents of C and recalcitrant constituents, (i.e. lignin and polyphenols) of the residues. Dipterocarp, a resistant residue, showed the highest LF‐C, followed by the intermediate residues, tamarind, and groundnut, whereas HF was higher in groundnut and tamarind than dipterocarp residues. Rice straw had the lowest LF‐ and HF‐C contents. Tamarind had the highest quantity (51 per cent) of small macroaggregates (0·25–2 mm), while dipterocarp had the most (2·1 per cent) large macroaggregates (>2 mm). Rice straw had the lowest quantities of both macroaggregates. Similar to small‐sized HF (0·05–0·25 mm), small macroaggregates had positive correlation with N and negative correlation with C/N ratios, while large macroaggregates had positive correlations with C and recalcitrant constituents of the residues. Tamarind, with intermediate contents of N and recalcitrant compounds, appears to best promote small macroaggregate formation. Carbon stabilized in small macroaggregates accounted for the tamarind treatment showing the largest SOC accumulation. Copyright © 2010 John Wiley & Sons, Ltd.     

Restoration of Plant and Animal Communities in a Sanitary Landfill: A 10‐year Case Study in Hong Kong

This study was conducted in the South East New Territories landfill in Hong Kong, with the objectives to (i) investigate the plant and animal communities' establishment and performance within 10 years after restoration and (ii) provide important information on pioneer plants species selection recommendations for restoring sanitary landfills. The studying sites were re‐vegetated in 2003, with 14 pioneer plant species, including Acacia auriculiformis, A. confusa and Schefflera heptaphylla, planted. In total, four permanent quadrats (10 m × 10 m) were used for monitoring at three restored sites (sites E, N and S) and the control site C. The soil properties and plant and animal communities inside plots were investigated annually in summer and winter between 2003 and 2014. The similarity of plant and animal communities between the restored and control sites was compared using Jaccard's index. Ten years after restoration, animal and plant communities were gradually established at all sites. No animal was introduced into the restored sites in 2003; however, there were 29, 31 and 44 animal species recorded at sites E, N and S, respectively, between 2003 and 2012. Within the studying period, 38 plant species (trees: 52·63%, shrub: 21·05%, herbs: 23·68% and climber: 2·63%) were recorded in all sites and 17 (36·84%) of them were self‐seeding. Exotic species, such as those from the family Acacia and Mimosaceae, were dominant at all restored sites, which implies that exotic species are more competitive and suitable to be used as pioneer species in sanitary landfill restoration. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of long‐term fertilization on the transformations of water‐extractable phosphorus in a fluvo‐aquic soil

Improved information on water‐extractable soil P (P_w) and its distribution in various forms is needed to assess its bioavailability and environmental impact. This study investigated P_w in a fluvo‐aquic soil solution in relation to the continuous application of inorganic fertilizer (NPK) and wheat straw–soybean‐based compost for 15 y. Phosphatase‐hydrolysis techniques were used to fractionate organic P (P_o) in water extracts of soil into phosphomonoester (P_om) and phosphodiester (P_od). In comparison with the noncomposted treatments, compost application significantly increased the levels of inorganic P (P_i) and P_o. P_om was the main form in water‐extractable soil P_o (71%–88%), in which sugar phosphate (P_os) occupied 48%–75%, inositol hexakisphosphate (P_op) comprised 13%–23%, and P_od only accounted for a small percentage (11%–26%). Long‐term compost application significantly increased the content of P_om, P_os, and P_od, but decreased the P_op content; the ratio of P_om to P_o increased significantly in compost‐treated soil, but the ratio of P_op to P_o and P_od to P_o significantly decreased. Thus, the equilibrium of phosphatase involved P transformations shifted to P_i in compost‐treated soil. The phosphomonoesterase and phosphodiesterase activities were significantly higher in compost‐treated soil, which favored the transformations of P_od into P_om and P_om into P_i. The ratio of P_o to P_w in water extracts of compost‐treated soil was similar to that of control soils with no fertilizer input (CK), but was significantly lower than in NPK treatment, which demonstrated that a larger increase occurred for soil P_i in water extracts of compost‐treated soil. Long‐term compost application in the fluvo‐aquic soil changed the composition of P_w, promoted the rate of P transformations in soil solution, and significantly increased soil P bioavailability.     

Carbon stocks and carbon fluxes from a 10‐year prescribed burning chronosequence on a UK blanket peat

Prescribed burning is a common land management technique in many areas of the UK uplands. However, concern has been expressed at the impact of this management practice on carbon stocks and fluxes found in the carbon‐rich peat soils that underlie many of these areas. This study measured both carbon stocks and carbon fluxes from a chronosequence of prescribed burn sites in northern England. A range of carbon parameters were measured including above ground biomass and carbon stocks; net ecosystem exchange (NEE), net ecosystem respiration (R_eco) and photosynthesis (P_g) from closed chamber methods; and particulate organic carbon (POC). Analysis of the CO₂ data showed that burning was a significant factor in measured CO₂ readings but that other factors such as month of sampling explained a greater proportion of the variation in the data. Carbon budget results showed that whereas all the plots were net sources of carbon, the most recent burn scars were smaller sources of carbon compared with the older burn scars, suggesting that burning of Calluna‐dominated landscapes leads to an ‘avoided loss’ of carbon. However, this management intervention did not lead to a transition to a carbon sink and that for carbon purposes, active peat‐forming conditions are desirable.     

Effects of grazing strategy on limiting nitrate leaching in grazed grass‐clover pastures on coarse sandy soil

Urinations of ruminants on grazed pastures increase the risk of nitrate leaching. The study investigated the effect of reducing the length of the grazing season on nitrate leaching from a coarse sandy, irrigated soil during 2006–2007 and 2007–2008. In both years, precipitation was above the long‐term mean. The experiment was initiated in a 4‐yr‐old grass‐clover sward in south Denmark. Three treatments were as follows grazing only (G), spring cut followed by grazing (CG) and both spring and autumn cuts with summer grazing (CGC). Nitrate leaching was calculated by extracting water isolates from 80 cm depth using ceramic suction cups. Because of considerable variation in measured nitrate concentrations, the 32 installed suction cups per treatment were insufficient to reveal differences between treatments. However, weighted nitrate leaching estimations for G, CG and CGC showed estimated mean nitrate N concentrations of 23, 19 and 13 mg/L for an estimated proportion area occupied by urine patches of 0.33, 0.26 and 0.16, respectively. Thus, N concentrations in G and CG exceeded the EU limit of 11.3 mg N/L. Under the prevailing conditions, the time of urination did not appear important. The estimated background leaching calculated from suction cups presumably not situated under urine patches resulted in mean nitrate N concentrations of 2.6 mg/L.