CHAPTER 5 Control of Diffuse Pollution by Mid-Field Shelterbelts and Meadow Strips Lech Ryszkowski, Lech Szajdak, Alina Bartoszewicz, and Irena yczy ska-Ba oniak CONTENTS Introduction Environment of the Turew Agricultural Landscape Nitrogen Compounds in the Drainage System of the Turew Landscape Control of Mineral Nitrogen Pollution by Shelterbelts and Meadows Processing of Mineral Nitrogen in the Biogeochemical Barriers Landscape Management Guidelines for Efficient Control of Nitrogen Pollution Prospects for Control of the Diffusion Pollution through Management of Landscape Structure References INTRODUCTION Water quality is one of the fundamental requisites for sustainable development of agriculture, and it constitutes the survival determinant of rich plant and animal assemblages. Interactions among physical, chemical, and biological processes char- acteristic of a watershed determine discharged water quality; alteration of any one of these processes will affect one or more water quality properties. This fact was recently learned by scientists and the public when growing problems of water contamination were unsuccessfully tackled with only technical measures (water purification plants). Activities aiming at water pollution control in the 1970s and up to the mid-1980s focused on treating urban and industrial sewage effluents — that · Z ´ nl 0919 ch05 frame Page 111 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC is, on the control of point sources of pollution by construction of water purification plants (Vollenweider 1968). Success was achieved in some reservoirs, such as Lake Constance, but eutrophication problems could not be totally eliminated, and, in addition, such problems started to appear even in water bodies located far away from point sources of pollution (Halberg 1989, Kauppi 1990). As agricultural production intensified, land-use changes caused by agriculture became more apparent. Enlargement of farm sizes was linked to more efficient use of machines, which decreased costs of the cultivation of large fields not segmented by shelterbelts (mid-field rows of trees), open drainage ditches, and other obstacles to fast and powerful agricultural equipment. This trend of agricultural development resulted in homogenizing the countryside structure. For example, in France the average farm size increased from 19 to 28 ha in the period from 1970 to 1990. In the same time span, the average farm size in the U.K. increased from 54 to 68 ha, in West Germany from 13 to 18 ha, and in Belgium from 8 to 15 ha (Stanners and Bourdeau 1995). Consolidation and expansion of cultivated fields led to eradication of field margins, hedges, shelterbelts, small mid-field ponds or wetlands, and other nonproductive elements of the landscape. Thus, for example, 22% of hedgerows in the U.K. were eliminated by the mid-1980s (Mannion 1995). The disappearance rate of wetlands in the European Union, excluding Portugal, has amounted to 0.5% annually since 1973 (Baldock 1990). In Denmark, 27% of small water reservoirs disappeared from 1954 to 1984 (Bülow-Olsen 1988). By intensifying production, farmers interfere with patterns of element cycling in landscapes using fertilizers and pesticides, and they are changing water regimes by drainage or irrigation. Feedback of the agricultural measures of production as well as induced changes in land use brought environmental problems, such as impoverishment of biological diversity or nonpoint (diffuse) water pollution. In the 1980s, it was recognized that control of point sources of pollution could not alone solve the problems of water quality. The water pollution, especially with nitrates, was detected in streams or lakes located far from urban or industrial point sources (Omernik et al. 1981, OECD 1986, Halberg 1989, Ryszkowski 1992). The diffuse water pollution problems were recognized worldwide in the 1990s. Nonpoint water pollution is attributed to human-induced, above-natural-rate inputs of chemical compounds into subsurface and surface water reservoirs. At present, agriculture is undoubtedly the main reason for diffuse pollution problems (OECD 1986, Rekolainen 1989, Kauppi 1990, Ryszkowski 1992, Flaig and Mohr 1996, Johnsson and Hoffmann 1998). High concentrations of nitrates exceeding 50 mg per liter of soil solution were detected in Germany, northern France, eastern England, northwestern Spain, northern Italy, and Austria. Very high nitrate concen- trations were detected in Denmark, the Netherlands, and Belgium (Stanners and Bourdeau 1995). So, at the beginning of the 1990s, it appeared that modern intensive agriculture practices were threats to the environment and that the Common Agri- cultural Policy (CAP) of the European Union should be changed by introduction of more environmentally friendly technologies (Stern 1996). Simultaneous with growing concerns about diffuse pollution were studies show- ing that permanently vegetated land strips could control inputs of chemicals from cultivated fields to waterbodies (Pauliukevicius 1981, Lowrance et al. 1983, Peterjohn 0919 ch05 frame Page 112 Wednesday, November 21, 2001 1:50 PM © 2002 by CRC Press LLC and Correll 1984, Pinay and Decamps 1988, Ryszkowski and Bartoszewicz 1989, Muscutt et al. 1993, Hillbricht-Ilkowska et al. 1995, and others). The majority of the studies concerned riparian plant buffer zones and their efficiency for the control of diffuse pollution. A thorough review of the riparian-strip functions for controlling diffuse pollution, both via surface and subsurface fluxes, published by Correll (1997) in proceedings of the 1996 buffer zone symposium, provides a review of studies on various aspects of diffuse pollution control (Haycock et al. 1997). A recent book edited by Thornton et al. (1999) addresses primarily the nonpoint pollution impacts on lakes and reservoirs, stressing the practical aspects of the control. As stated above, most studies concerned protection of surface water reservoirs from diffuse pollution by riparian vegetation strips. Field studies have shown, for example, that nitrates are efficiently removed from shallow ground water passing through the root system of plants in a buffer zone. Mechanisms responsible for that process are still elusive (Correll 1997), but it is generally assumed that the following processes are important: ion exchange capacities of soil, plant uptake, and denitrification. Long-term studies on the function of shelterbelts and stretches of meadows within the Turew agricultural landscape, carried out by the Research Centre for Agricultural and Forest Environment, Polish Academy of Sciences, provided infor- mation on control of diffuse pollution in upland parts of drainage areas, which enriched knowledge on control of nonpoint pollution outside riparian zones. Those studies also disclosed some mechanisms for a ground water pollution control, which can be useful for developing a strategy of water resource protection. Review of these studies will be used to evaluate the prospect for diffuse pollution control in agricul- tural landscapes. ENVIRONMENT OF THE TUREW AGRICULTURAL LANDSCAPE The Turew landscape (about 17000 ha) has been the object of long-term studies on agricultural landscape ecology (Ryszkowski et al. 1990, 1996), and detailed characteristics of climate, soils, hydrology, and land-use forms can be found in those publications. The landscape is identified by the adjacent village, Turew. The terrain consists of a rolling plain, made up of slightly undulating ground moraine. Differ- ences in elevation do not exceed a few meters. In general, light soils are found on the higher parts of the landscape with favorable infiltration conditions (glossudalfs and hapludalfs). Endoaquolls and medisaprists occur in small depressions. The infiltration rates of upland soils range from a few to several cm·h –1 and can be classified as having moderate or moderately rapid infiltration rates. Thus, the water from rain or snow thaw can easily infiltrate beyond the depth of plant roots and then transport dissolved chemical compounds to ground water; however, in layers below 60 cm (argillic and parent material horizons) infiltration rates are slowed due to higher clay content. The content of organic carbon in the ochric horizon (upper horizon of soil) of upland soils ranges from 0.5 to 0.8%, total nitrogen amounts from 0.05 to 0.08%, and the ratio of C:N changes from 8:1 to 11:1 (Table 5.1). Soil reaction in the ochric and luvic horizons varies generally between 4.5 and 5.5 pH KCL . In deeper parts of the soil profile, soil reaction approaches neutral or slightly alkaline 0919 ch05 frame Page 113 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC Table 5.1 Means of Physical and Chemical Characteristics of Hapludalfs and Glossudalfs Soil Horizon Thickness (cm) Organic C (%) N Total (T) Contents of Clay Below 0.002 mm (%) CEC mmol (+)·kg –1 S mmol (+)·kg –1 BS (S:CEC) (%) Ochric Luvic Argillic Parent material 30.8 ± 3.1 26.9 ± 7.4 37.8 ± 12.6 — 0.62 ± 0.14 0.21 ± 0.12 n.d. n.d. 0.075 ± 0.019 0.025 ± 0.012 n.d. n.d. 3.1 ± 1.2 2.7 ± 0.9 14.2 ± 3.7 11.9 ± 3.3 49.2 ± 1.2 34.8 ± 0.9 95 ± 1.7 81.2 ± 1.9 30.4 24.6 71.7 66.8 61.8 70.7 75.2 82.3 CEC — cation exchange capacity; S — sum of bases; BS — percent of saturation with bases n.d. — not determined Source: Bartoszewicz 2000. 0919 ch05 frame Page 114 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC values of pH KCL . The alkaline reaction is caused by the presence of calcium carbon- ates in the boulder loam. The low values of cation exchange capacities of the soil, as well as small amounts of clay fractions and organic matter, indicate that with fast percolation of water there is intensive leaching of chemical solutes. Thus one can infer that sorption of ammonia ions as well as other cations is rather low in the upper horizons of soils located in the upland parts of the landscape and moderately low in deeper layers. The opposite situation is observed in endoaquolls and medisaprists situated in the depressions of the landscape. These soils are characterized by much higher contents of organic carbon (2.7 to 43.4%) and are poor or very poorly drained. Their adsorptive capacities for passing cations depends mainly on the content of organic matter because clay minerals are poorly represented. Pokojska (1988) has found positive correlation (r = 0.72) between values of cation exchange capacities and the percentage of organic carbon content in those soils. Thus endoaquolls and medisaprists of the Turew landscape have high potential to adsorb cations (Pokojska 1988, Marcinek and Komisarek 1990). The area, from a Polish perspective, is warm, with an annual mean temperature of 8°C. Thermal conditions are favorable for vegetation growth. The growing season, with air temperatures above 5°C, lasts 225 days. On average, it begins March 21 and ends October 30. Mean corrected annual precipitation (1881–1985) amounts to 590 mm (uncorrected value to 527 mm). Although the amount of precipitation in the spring-summer period is more than twice that in winter, a water shortage often occurs in the summer. The annual evapotranspiration rate averages about 500 mm and runoff is 90 mm. Since a majority of the soils are characterized by high rates of infiltration, their water storage is not of great importance in dry summers. Water deficits are further intensified by drainage of a considerable part of the area. The most advantageous component of the landscape is its shelterbelts (rows or clumps of trees), which were planted in Turew due to the initiative of Dezydery Ch apowski in the 1820s. In addition to shelterbelts, small afforestations are found in the landscape. Shelterbelts and afforestations cover 14% of the entire area and are composed of Pinus sylvestris (65.5% of total afforested area), Quercus petraea and Q. robur (14.5%), Robinia pseudoaccacia (5%), Betula pendula (4.3%) and others, totaling 24 tree species. But in shelterbelts oaks, false acacias, maples, lindens, larch, and poplars prevail. Oaks and larches have very deep root systems, while maples (especially sycamore maples) and lindens have moderately deep roots with broad root systems. The mix of the tree species creates a better screen to the seeping solutes in ground water than would a shelterbelt composed of one species (Prusinkiewicz et al. 1996). Cultivated fields cover 70% of the area. During the last 10 years, there has been a tendency for increased cereals (wheat, barley, rye, oats) in the crop rotation pattern, and it presently comprises 70% of arable land. Decreased row crops and pulse crops are also characteristic. Meadows and pastures located in depressions close to channels, ponds, and lakes and among cultivated fields cover 12% of the area. Hay forms the largest component of grasslands, but other important associations are made by sedge meadows in wetlands. The rest of the land is l 0919 ch05 frame Page 115 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC composed of lakes and mid-field ponds and channels, waterlogged areas, roads, and villages. The density of small reservoirs varies from 0.4 to 1.7/km 2 . Mineral fertil- ization varied from 220 to 315 kg NKP/ha but since 1991 about a 40 to 50% decrease or greater in mineral fertilization was observed on some small farms because of the economic crisis associated with the change of the political system. Yields are high for cereals (rye, wheat, barley and oats), ranging from 3.2 t·ha –1 to about 4 t·ha –1 . The level of mechanization of field labor is high, amounting on the average to 1 tractor per 17 ha of cultivated fields. In studies on the impact on ground water chemistry from the mid-field affores- tations and shelterbelts or strips of meadows (called biogeochemical barriers), the dominant direction of subsurface water pathways was estimated by measurement of ground water table elevation in wells located in fields and adjoining shelterbelts, small forests, or meadows. The samples for nitrogen compound concentration meas- urements were collected from wells, drainage pipes, ditches, small ponds, and main drainage canals of the landscape over different periods but never during a time span shorter than 1 year. Over the last 200 years, there were important habitat changes connected with land reclamation activities leading to drying of the area. The effects are observed not only in the drop in the ground water level but also in soil degradation caused by drainage. So, for example, fertile endoaquolls have been converted in many places into glossudalfs or hapludalfs with low carbon content. Thus, drying of the region is expressed in soil changes; although appearing slowly, the nature of the trend can be clearly recognized. NITROGEN COMPOUNDS IN THE DRAINAGE SYSTEM OF THE TUREW LANDSCAPE The Turew landscape is drained by a canal about 4 m wide with an average long- term water depth of 0.6 m. The annual mean concentrations of N-NO 3 –1 varied irregularly from 0.5 mg·dm –3 to 3.4 mg·dm –3 . Almost the same range of variation in N–NH 4 + concentration was observed (Figure 5.1). At the beginning of the 1990s, there was a decline in the use of fertilizers due to the economic crisis, amounting to a drop in application of 40 to 50%. But despite decreased input of fertilizers, the level of inorganic ion concentrations of nitrogen did not change, showing irregular cycles with a peak in 1993 and 1994, followed by a drop and then increasing since 1997 (Figure 5.1). Mean concentrations of the mineral forms of nitrogen in the canal water during the period 1973–1991, when higher doses of fertilizers were applied, were 1.40 mg·dm –3 for N–NO 3 – and 1.70 mg·dm –3 for N–NH 4 + . In the period 1992–2000 when fertilizer use dramatically decreased, the mean concentration increased to 2.04 mg·dm –3 in the case of N–NO 3 – and to 1.81 mg·dm –3 for N–NH 4 + . Thus, the relationship between input of fertilizer and output of nitrogen ions from the watershed is not linear and is sub- stantially modified by the buffering capacities of the total drainage area. The storage capacities of various elements in the landscape for nitrogen, as well as options for 0919 ch05 frame Page 116 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC Figure 5.1 Mean annual concentration in main drainage canal of the Turew landscape. 0 0.5 1 1.5 2 2.5 3 3.5 1 973 1974 1975 1976 1977 1978 1979 1980 1 981 1982 1983 1984 1985 1986 1 987 198 8 19 89 1 99 0 1 99 1 1 99 2 1 99 3 19 94 1 995 19 96 19 97 19 98 199 9 2 000 Concentration [mg·dm -3 ] N – NO 3 - N – NH 4 + 0919 ch05 frame Page 117 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC diverting nitrogen compounds into various routes of discharge (water runoff, vola- tilization), not only condition lag responses but also obscure the relationships between fertilizer input and their concentrations in water of the drainage system. The long-term (28 years) average concentration of both mineral forms of nitrogen was the same in the main canal of the Turew landscape — 1.69 mg·dm –3 in the case of N–NO 3 – and 1.74 mg·dm –3 for N–NH 4 + . Analysis of changes of N–NO 3 – and N–NH 4 + ions over 28 years showed that the changes are independent (correlation coefficient r = –0.06 is not statistically significant), which is another indication of the complex transformation of nitrogen in the landscape. When the concentrations of nitrogen forms were analyzed with respect to the monthly changes during the year, distinct seasonal differences were found between the cold and growth seasons (Bartoszewicz 1994). During the winter (December–February), the monthly mean nitrate concentration was highest, reaching 2.79 mg·dm –3 (Table 5.2) while its value during the full plant growth season (May–September) was lowest. When the plant’s transpiration processes decreased in October and November (leaf shedding by decid- uous trees, drying of grasses, and only small plants of winter crops present in cultivated fields), nitrate concentration increased so as to reach the highest values when biological activity is retarded in winter. Concentrations of N–NH 4 + cations did not show such distinct changes in the course of seasons although some drop during the plant growth season can be easily observed (Table 5.2). In the course of the entire year, nitrates show much higher variance of concentrations than ammonium. It seems the reason for this difference is connected with the fact that biological activity is in “full swing” during the warm season, although pinpointing the specific process responsible (plant uptake, denitri- fication, assimilatory or dissimilatory nitrate reduction) requires additional studies. In the plant growing season (end of March until the end of October), average precipitation reaches 410 mm out of an annual total of 590 mm (Wo and Tamulewicz 1996). Despite high precipitation rates in summer, the concentrations of nitrates in water of the canal were low in this period, although N–NO 3 – anions are easily leached from soil. Thus, effects of mineral nitrogen leaching caused by rainfall are modified by influences exerted by plants on migrating nitrogen ions in the watershed. (This conclusion is confirmed by special studies carried out in small watersheds, the results of which are discussed later in this chapter.) The differences between nitrate concentrations in ground water under cultivated fields and their concentrations in water of the main drainage canal clearly show modification effects exerted by the landscape structure on dispersion of chemical Table 5.2 Mean Monthly Long-Term (1973–2000) Concentrations (mg·dm –3 ) of Inorganic Nitrogen Forms in Main Drainage Canal of the Turew Landscape in Consecutive Periods of the Year Period Dec.–Feb. March–April May–Sept. Oct.–Nov. N–NO 3 – 2.79 ± 1.01 2.50 ± 0.71 0.88 ± 0.15 1.11 ± 0.48 N–NH 4 + 1.98 ± 0.30 1.92 ± 0.44 1.68 ± 0.19 2.10 ± 0.37 ´ s 0919 ch05 frame Page 118 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC compounds. Analyses of mineral nitrogen distribution in the unsaturated zone below the cultivated field showed that in the spring large amounts are leached into the ground water. In ground water of some fields, high concentrations of N–NO 3 – , reach- ing 60 mg·dm –3 , can be found when fertilizers were applied during spring (Rysz- kowski et al. 1997). But despite the fact that such situations occur in some fields, each spring the monthly concentrations of nitrates in the main canal draining the total area are very low, which again indicates strong modification effects of landscape structure on the control of diffuse pollution. CONTROL OF MINERAL NITROGEN POLLUTION BY SHELTERBELTS AND MEADOWS When ground water carrying nitrates is within direct and indirect (capillary ascension) reach of the root system, nitrate concentrations are substantially decreased. Knowing that the NO 3 – anion is practically not exchanged by soil colloids, these differences result mainly from the action of a complex set of biological factors involving the plant’s uptake, denitrification processes, and release of gaseous prod- ucts including NO, N 2 O, and N 2 . In addition, nitrates may undergo reduction to NH 4 + , which could be volatilized. The regulation of those processes under field conditions is poorly understood (Correll 1997). The reduction of nitrates when ground water is seeping under shelterbelts, afforestations, or grasslands is pronounced, and under the Turew landscape condi- tions such reduction varied from 63 to 98% for shelterbelts and afforestations (Table 5.3). In the case of meadow strips, the reduction varied from 79 to 97%. Table 5.3 Mean Concentrations of N–NO 3 – (mg·dm –3 ) in Ground Water under Cultivated Fields, Shelterbelts, Small Forests, and Meadows in the Turew Agricultural Landscape Period of Sampling Cultivated Field (a) Shelterbelt or Forest Patch (b) Meadow (b) Reduction (a-b):a (%) Reference 1982–1986 1982–1986 1972–1973 1984–1986 1994 1995 1986–1989 1987–1989 1987–1991 1993 1993 1994 1994 1995 22.2 37.6 12.6 33.1 52.4 13.1 48.3 15.9 13.1 18.7 22.1 19.1 13.4 18.3 1.0 1.1 0.3 8.1 2.7 4.9 — — — — — — — — — — — — — — 6.5 0.7 2.8 1.4 2.0 1.2 2.4 0.6 95 97 98 75 94 63 87 95 79 92 91 94 82 97 Bartoszewicz and Ryszkowski 1996 Bartoszewicz and Ryszkowski 1996 Margowski and Bartoszewicz 1976 Ryszkowski et al. 1997 Ryszkowski et al. 1997 Ryszkowski et al. 1996 Bartoszewicz 1990 Bartoszewicz 1990 Szpakowska and yczy ska-Ba oniak 1994 Ryszkowski et al. 1996 Ryszkowski et al. 1996 Ryszkowski et al. 1996 Ryszkowski et al. 1996 Ryszkowski et al. 1996 · Z ´ n l 0919 ch05 frame Page 119 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC Thus, both kinds of biogeochemical barriers (shelterbelts and meadow stretches) showed similar efficiency of nitrate reduction. Results are similar to the estimates gathered from various literature sources by Muscutt et al. (1993). One can argue that changes in concentrations do not fully show the effects of nitrate limitation exerted by the biogeochemical barriers. The control effects depend on both the changes in concentrations and the rate of N–NO 3 – flux through the barrier. Low concentration inflow can provide a large amount of chemicals if the rate of water flux is high. But the hydraulic conductivity of soils (up to 1.0 m·day –1 ) as well as hydraulic gradients of ground water tables that determine flux are small in the landscape studied, which should render good approximations of nitrate fluxes by changes in their concentrations. This situation was confirmed by studies of the hydrology of water seeping under biogeochemical barriers (Ryszkowski et al. 1997). Estimated N–NO 3 – ratios for output-input of annual flux estimates for birch mid-field forests amounted to 0.22, 0.25, and 0.28 in three consecutive years (Ryszkowski et al. 1997). The average for the 3 years was 0.25, which corresponds well with the estimate based on concentration changes, which was also 0.25. In the case of the pine mid-field forest, both estimates also match very well (Ryszkowski et al. 1997). Thus, in an area where the slope of the ground water table is not too steep, the differences in concentrations of chemical compounds between an input and output characterize well the flux control efficiency of the barrier. Studies (Ryszkowski and K dziora 1993) indicate that, as the steepness of slope increases, the shelterbelt and meadow are less efficient in regulating ground water flow and chemicals transported. A great influence of plant cover structure on output of elements from watersheds was shown by Bartoszewicz (1994), and Bartoszewicz and Ryszkowski (1996). These studies were carried out in two small watersheds. The first was a uniform watershed (174 ha) covered 99% by cultivated fields and 1% by small afforestation. The second watershed (117 ha) was mosaic; cultivated fields made up 84% of the area, meadows 14%, and riparian afforestation 2%. During the 3-year period, the mean annual water output was 102.0 dm 3 ·m –2 from the uniform watershed and 70.2 dm 3 ·m –2 from the mosaic watershed. The mean annual precipitation for both water- sheds was the same, amounting to 514 dm 3 ·m –2 , so the lower water runoff from the mosaic watershed was due to higher evapotranspiration rates characteristic of affor- estations and grasslands (Ryszkowski and K dziora 1987). This is clearly seen when water outputs are analyzed from both watersheds in summer (Table 5.4). The water runoff from both watersheds during the hydrological years 1988/1989–1990/1991 differed by 32 mm on average. However, the water runoff during the winter half-years was almost the same from either watershed, whereas during the growing season water outputs from the uniform watershed (per unit of area) were three times higher than those from the mosaic watershed (Bartoszewicz 1994). Thus, shelterbelts and meadows making up 16% of the mosaic watershed area very effectively controlled output of water from the catchment area into the drainage canal during the plant growing season (Table 5.4). From a uniform arable watershed, 20.4 kg of inorganic nitrogen had leached out from 1 ha annually, 20% of which was in the form of ammonium ions. Thus the ˛e ˛e 0919 ch05 frame Page 120 Tuesday, November 20, 2001 6:25 PM © 2002 by CRC Press LLC [...]... 7-Year-Old 140-Year-Old UA ON UA ON Fields Adjoining to Shelterbelts 7-Year-Old 140-Year-Old UA ON UA ON March 12 April 7 May 8 June 5 July 9 August 20 September 14 October 12 November 14 4. 35 4.81 4 .56 4. 25 6.20 9.17 7.76 5. 07 4. 35 590 .5 591.8 609.1 52 7.3 602.7 57 1.4 53 8.4 657 .3 54 9.1 16.88 14 .50 18.96 5. 32 4.88 3 .58 7.94 4. 05 2. 15 1634.3 1677.3 1416 .5 254 1.4 56 44.9 3400.7 2138.0 3133.0 2320.7 6. 45. .. 2. 15 1634.3 1677.3 1416 .5 254 1.4 56 44.9 3400.7 2138.0 3133.0 2320.7 6. 45 5.98 7. 25 5.27 5. 30 8.40 5. 30 3.40 3.07 354 .8 350 .6 355 .1 497.1 421.2 472.4 50 6.4 488.9 50 1.2 4 .53 4.38 3.94 2 .50 2.67 6.41 7.92 2.63 1.93 58 7 .5 567.8 53 3.3 789.1 57 6.7 56 6.1 460.3 52 1.1 50 6.9 Mean 5. 61 58 1.9 8.69 2 656 .3 5. 60 438.6 4.10 56 7.6 Date According to the review by Bremner and Mulvaney (1978), urease activity is positively... 0919 ch 05 frame Page 132 Tuesday, November 20, 2001 6: 25 PM Plant growth season excluding heavy rains 16 y = 8.6287e-0. 05 N-NO3 [mg ·l-1] 14 12 R2 = 0.8114 10 8 6 4 2 0 0 10 20 30 40 50 Share of nonarable area [%] Winter season 16 y = 10.626e-0.0 35 14 R2 = 0.9616 N-NO3 [mg· l-1] 12 10 8 6 4 2 0 0 5 10 15 20 25 30 35 40 45 50 Share of nonarable area [%] Heavy rains during plant growth season 16 N-NO3 [mg·... season 16 N-NO3 [mg· l-1] 14 y = 14. 251 e-0.02 12 R2 = 0.9101 10 8 6 4 2 0 0 5 10 15 20 25 30 35 40 45 50 Share of nonarable area [%] Figure 5. 2 – In uence of plant cover structure (x) on N–NO3 concentration (y) in water output from small drainage basins © 2002 by CRC Press LLC 0919 ch 05 frame Page 133 Wednesday, November 21, 2001 1 :51 PM rains amounted to 106.4 mm, and at the beginning of July there was... 119 120 141 146 167 159 155 123 119 Mean 83.8 138.8 Fields Adjoining Shelterbelts 7-Year-Old 140-Year-Old 82 82 87 91 1 15 107 87 83 85 91 79 78 81 100 129 99 83 80 68 88.6 With increasing age of shelterbelt, more and more nitrogen is stored in the resistant-to-decomposition organic compounds The accumulation of soil organic matter under shelterbelts is the main mechanism of long-term withdrawal of various... (mg·dm–3) in Ground Water Seeping through Old Afforestations Calculated from Monthly Samples in 1997 Form of Nitrogen – N–NO3 + N–NH4 Total mineral nitrogen Dissolved organic nitrogen Location of Piezometers in Distance from the Field-Park Boundary (m) 0 16 .5 62 5. 3 3.1 8.4 7.4 6.4 3.1 9 .5 5.6 14.2 2.9 17.1 4 .5 Results of long-term studies in the Turew landscape recommend the following guidelines for... 2002 by CRC Press LLC 0919 ch 05 frame Page 123 Tuesday, November 20, 2001 6: 25 PM + – Table 5. 6 Distribution of N–NO3 and N–NH4 (g·m–2) in the Unsaturated Layers of Soil in the Cultivated Field and Adjoining Pine Afforestation Sampling Term Mineral Form of N Cultivated Field Soil Layer Depth (cm) 0–80 81– 150 0– 150 Pine Afforestation Soil Layer Depth (cm) 0–80 81– 150 0– 150 April 1986 – N–NO3 (a) + N–NH4... most intensive evolution of the nitrous oxide from soil was also observed in the summer (Table 5. 10) Table 5. 10 N2O Evolution (N ␮g·m–2 ·h–1) from Soil in Shelterbelts of Various Ages and Adjoining Cultivated Fields Date Shelterbelts 7-Year-Old 140-Year-Old March 12 April 7 May 8 June 5 July 9 August 20 September 14 October 12 November 14 Mean © 2002 by CRC Press LLC Fields Adjoining Shelterbelts 7-Year-Old... Fields Adjoining Shelterbelts 7-Year-Old 140-Year-Old 80 80 80 120 120 110 100 90 100 120 110 130 130 180 170 150 150 140 200 240 220 370 320 250 190 200 170 250 230 250 270 280 270 250 240 240 97 142 240 253 0919 ch 05 frame Page 129 Tuesday, November 20, 2001 6: 25 PM From the soil of cultivated fields, where nitrates prevail over ammonium ions (Tables 5. 3, 5. 6, and 5. 7), much higher rates of N2O evolution... cultivation for 6 years, very low concentrations of mineral nitrogen were detected in comparison with an adjoining cultivated field (Table 5. 7) When inputs of fertilizers into soil under a growing shelterbelt were ceased, the amount of mineral nitrogen dramatically decreased almost 10 times in comparison with a field in October 1999 and 5 times in May 2000 when mineral nitrogen was regenerated due to greater . 14 4. 35 4.81 4 .56 4. 25 6.20 9.17 7.76 5. 07 4. 35 590 .5 591.8 609.1 52 7.3 602.7 57 1.4 53 8.4 657 .3 54 9.1 16.88 14 .50 18.96 5. 32 4.88 3 .58 7.94 4. 05 2. 15 1634.3 1677.3 1416 .5 254 1.4 56 44.9 3400.7 2138.0 3133.0 2320.7 6. 45 5.98 7. 25 5.27 5. 30 8.40 5. 30 3.40 3.07 354 .8 350 .6 355 .1 497.1 421.2 472.4 50 6.4 488.9 50 1.2 4 .53 4.38 3.94 2 .50 2.67 6.41 7.92 2.63 1.93 58 7 .5 567.8 53 3.3 789.1 57 6.7 56 6.1 460.3 52 1.1 50 6.9 Mean. 12 November 14 4. 35 4.81 4 .56 4. 25 6.20 9.17 7.76 5. 07 4. 35 590 .5 591.8 609.1 52 7.3 602.7 57 1.4 53 8.4 657 .3 54 9.1 16.88 14 .50 18.96 5. 32 4.88 3 .58 7.94 4. 05 2. 15 1634.3 1677.3 1416 .5 254 1.4 56 44.9 3400.7 2138.0 3133.0 2320.7 6. 45 5.98 7. 25 5.27 5. 30 8.40 5. 30 3.40 3.07 354 .8 350 .6 355 .1 497.1 421.2 472.4 50 6.4 488.9 50 1.2 4 .53 4.38 3.94 2 .50 2.67 6.41 7.92 2.63 1.93 58 7 .5 567.8 53 3.3 789.1 57 6.7 56 6.1 460.3 52 1.1 50 6.9 Mean. Ecosystems in the Turew Landscape Date Shelterbelts Fields Adjoining to Shelterbelts 7-Year-Old 140-Year-Old 7-Year-Old 140-Year-Old UA ON UA ON UA ON UA ON March 12 April 7 May 8 June 5 July 9 August