LITHUANIAN UNIVERSITY OF AGRICULTURE WATER MANAGEMENT INSTITUTE OF LITHUANIAN UNIVERSITY OF AGRICULTURE Giedrius Baigys SOIL WATER REGIME AND NITRATE LEACHING DYNAMICS APPLYING NO-TILLAGE Summary of doctoral dissertation Technological Sciences Environmental Engineering and Land Management (04 T) Kaunas, 2008
The Doctoral Dissertation was carried out in the Water Management Institute of the Lithuanian University of Agriculture in 2004-2007. Scientific Supervisor : Dr. Ginutis Jokūbas Kutra (Water Management Institute of Lithuanian University of Agriculture, Technological Sciences, Environmental Engineering and Land Management 04T). The disertation is defended at the Council of Environmental Engineering and Land Management of the Lithuanian University of Agriculture: Chairman: Prof. Dr. Habil.Česlovas Linksmutis Ramonas (Lithuanian University of Agriculture, Technological Sciences, Environmental Engineering and Land Management 04T); Members: Prof. Dr. Habil. Albinas Kusta (Lithuanian University of Agriculture, Technological Sciences, Environmental Engineering and Land Management 04T); Prof. Dr. Habil. Brunonas Gailiuis (Lithuanian Institute of Energy, Technological Sciences, Environmental Engineering and Land Management 04T); Prof. Dr. Habil. Saulius Vaikasas (Water Management Institute of Lithuanian University of Agriculture, Technological Sciences, Environmental Engineering and Land Management 04T); Assoc. Prof. Dr. Sigitas Lazauskas (Lithuanian Institute of Agriculture, Biomedical Sciences, Agronomy 06B). Official opponents: Assoc. Prof. Dr. Arvydas Povilaitis (Lithuanian University of Agriculture, Technological Sciences, Environmental Engineering and Land Management 04T); Dr. Jūratė Kriaučiūnienė (Lithuanian Institute of Energy, Technological Sciences, Environmental Engineering and Land Management 04T). Defence of the doctoral dissertation will take place at the open session of the Council of Environmental Engineering and Land Management at 11 a.m. on December 18, 2008, in the hall No. 261 of the Central Building of the Lithuanian University of Agriculture. Address: Studentų11, Akademija, LT-53361, Kaunas r., Lithuania. The summary of the doctoral dissertation was distributed on 18thNovember, 2008. The dissertation is available at the libraries of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture.
LIETUVOS EMĖSŪKIO UNIVERSITETAS LIETUVOS EMĖSŪKIO UNIVERSITETO VANDENSŪKIO INSTITUTAS Giedrius Baigys DIRVOEMIO VANDENS REIMAS IR NITRATŲAZOTO IPLOVIMO DINAMIKA TAIKANT NEARIMINĮEMĖS DIRBIMĄ Daktaro disertacijos santrauka Technologijos mokslai, aplinkos ininerija ir kratotvarka (04T) Kaunas, 2008
Disertacija rengta 20042007 m. Lietuvos emėsūkio universiteto Vandensūkio institute. Mokslinis vadovas : Dr. Ginutis Jokūbas Kutra (Lietuvos emėsūkio universiteto Vandensūkio institutas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T). Disertacija ginama Lietuvos emėsūkio universiteto Aplinkos ininerijos ir kratotvarkos mokslo krypties taryboje: Pirmininkas: prof. habil. dr.Česlovas Ramonas (Lietuvos emėsūkio universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T); Nariai: prof. habil. dr. Albinas Kusta (Lietuvos emėsūkio universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T); prof. habil. dr. Brunonas Gailiuis (Lietuvos energetikos institutas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T) prof. habil. dr. Saulius Vaikasas (Lietuvos emėsūkio universiteto Vandens ūkio institutas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T); dr. (HP) Sigitas Lazauskas (Lietuvos emdirbystės institutas, biomedicinos mokslai, agronomija 06B). Oficialieji oponentai: Doc. dr. (HP) Arvydas Povilaitis (Lietuvos emėsūkio universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T); Dr. (HP) Jūratė Kriaučiūnienė energetikos institutas, technologijos (Lietuvos mokslai, aplinkos ininerija ir kratotvarka 04T). Disertacija bus ginama vieame Aplinkos ininerijos ir kratotvarkos krypties tarybos posėdyje 2008 m. gruodio 18 d. 11 val. Lietuvos emėsūkio universiteto centriniųrūmų261 auditorijoje. Adresas: Studentųg. 11, Akademijos mst., LT-53361 Kauno r., Lietuva Disertacijos santrauka isiuntinėta 2008 m. lapkričio 18 d. Su disertacija galima susipainti Lietuvos emėsūkio universiteto ir Lietuvos emėsūkio universiteto Vandensūkio instituto bibliotekose.
INTRODUCTION Relevance of Research Scientific research and the observations carried out by environmental ser-vices suggest that increased pollution of surface and ground waters with nitrates depends on agricultural production. Surface and ground waters running from fields to water bodies transport the nutrients that were not assimilated by plants and mi-croorganisms and were not absorbed by the soil. This reduces soil fertility and in-duces the development of blue-green algae, which produce toxic substances, in-crease turbidity and degradation of hydro fauna and flora. The means reducing the leaching of nutrients have to be fairly efficient and related with agricultural systems. Together with balanced fertilization and bet-ter conditions for taking up nutrients, e.g. cultivating plants of longer vegetation and catch crops, it is relevant to reduce the mineralization of the organic residues existent in soil and humus and to decrease its aeration. The systems of reduced and no-tillage, when ploughing is replaced with shallower tillage by disk implements or heavy cultivators (reduced tillage) or drilling is performed by special aggregates directly into stubble (no-tillage variant), are getting more popular in Lithuania. This tendency can be observed in other countries as well, the no-tillage system was applied on the areae.g. in 19731974 of 4,8 million ha in the USA and in 1997 this area increased to 20 million ha. That constituted about 16 % of the total arable land in the USA. In 19731974 in England the area with no-tillage applied was 200 thou. ha and in 10 years it reached 275 thou. ha. In early 70 ties of the 20thcentury in Germany the no-tillage system was practised only on the area which did not exceed 5 thou. ha. In Spain no-tillage is applied on 300350 thou. ha and in Italy on 100 thou. ha land area, which accounts for 2 % of the national agricultural land. Of Scandinavian countries only Norway is most interested in no-tillage as a means of reducing soil erosion. The reason making the major influence on farmers to reduce the intensity of soil tillage is economic with fuel and agricultural machinery getting more ex-pensive saving is getting more and more important. Deep ploughing of soil (depth of 4550 cm) is two times more expensive compared with ploughing at a depth of 35 cm and four times more expensive than ploughing at a depth of 15 cm(Hillel, 1991). Under the conditions of drier climate one of the factors determining the distribution of these technologies is saving soil moisture. No-tillage of soil resulted in much higher content of moisture in the surface soil layer (08 cm) in the middle of vegetation period compared with conventional methods (moisture difference made about 1015 % in volume)(Blevins et al., 1971). In Lithuania under the conditions of humid climate the lack of moisture is most often observed after sowing and during certain dry periods. Appropriate soil tillage in our conditions as well is an important means to control water regime. 3
Reduced tillage of land results in improved filtration properties of soil as so called macropore factor shows(Shipitalo et al., 2000); that has huge influence on the leaching of chemical substances from soil. As it is known, macropores (including cracks, eartworm tunnels and openings caused by roots) start on soil surface, go deeper and connect into a network. The research(Shipitalo et al, 1987) showed that applying no-tillage did not destroy macropore network, therefore, pore number per 1 m2 1500 and after using mouldboard ploughing only exceeded about 500. The macropore network conditions the situation when a large part of precipitation under gravitational forces does not filter to deeper soil surfaces through micropores between solid soil particles but goes down by macropore tubules. At a lesser contact of the water running down the macropores with the fine particles of nutrient leaching is reduced. The average leaching ofof soil the degree nitrate nitrogen from a no-tillage variant was 74 kg ha-1lower compared with a mouldboard ploughing variant(Weed et al., 1996). The impact of different agricultural systems used in agriculture on the leaching of nutrients and nitrates first of all depends on many factors that are not noticed and sometimes even underestimated by farmers trying to reach larger yields and better economic results. This article analyses the issue of changes in wa-ter regime and nitrate nitrogen leaching under the change of agricultural systems; such issue has not been investigated in Lithuania before. This research is especially relevant under the conditions of the Middle Lithuanian Lowland, where annual crops (cereals and sugar beet) area mainly cultivated, the ground is aerated in-tensely thus increasing the mineralization of organic substances and a lot of fertil-izers are used. Work Hypothesis Combination of reduced and no-tillage with other advanced agrotechnical means does not worsen soil hydrological conditions in the areas used for agriculture, they become favourable for achieving large yields of agricultural plants. the first year increases soil density andShallower tillage of soil during reduces porosity, however, an undisturbed system of macropores is maintained, which conditions a faster offtake of surplus water from a fully saturated layer and the improvement of aeration (first of all near macropores) and plant root development. In the areas of reduced land tillage soil moisture rises higher through unbroken capillaries from deeper layers and plants are better supplied with water during droughts. The dicreasse of aeration in the soil between macropores determines slower mineralization of organic substances and accumulation of humus. With increased plant supply with water and better taking of nutrients from soil water by plants and due to reduced mineralization of organic substances nutrient concentration in drainage water is lower and leaching is less in those periods, when outflow starts due to moisture surplus.
Work Objectiveis to establish the impact of reduced and no-tillage on the physical and hydrophysical properties of soil, moisture regime and nitrate nitrogen leaching in the areas of intensive agriculture. Work Tasks: • To establish the changes of soil physical and hydrophysical properties, water regime and matrix potential applying no-tillage. • To determine the impact of tillage on the level of ground water, drainage run-off and nitrate nitrogen concentrations in drainage water. • To identify the perspectivity of applying no-tillage and reduced tillage systems in a region of intensive agricultural production while introducing them as environmental measures reducing the pollution of drainage water with nitrates. Scientific Innovation and Its Importance A lot of in-depth experimental research has been carried out in Lithuania, which identified the impact of reduced and no-tillage systems on yield. However, the impact of these tillage systems on water regime and nitrate nitrogen leaching has not been properlyl investigated in Lithuania. For the first time in Lithuania this work: 1. Carried out in-depth investigations of soil moisture, drainage run-off and nitrate nitrogen leaching depending on tillage, physical and hydrophysical properties of soil and period wateriness. 2. Established relationship between drainage run-off, the amount of soil moisture, nitrate nitrogen resources in drainage water and environmental factors applying different tillage systems. 3. Analysed important efficiency of different tillage systems ecologically while reducing the pollution of water bodies. 4. Proposed preventive measures to reduce water pollution with nitrates. Thesis statements for defending: • the changes of soil physical properties (density increase,Due to porosity decrease) applying no-tillage systems does not have considerable negative influence on plants as the aeration of soil improves under the conditions of full saturation, water goes down through undisturbed macropores and plants are better supplied with water during droughts from deeper layers, when it rises through unbroken capillaries under the action of capillary potential of soil particles. • In reduced tillage systems applying shallower ploughing, tillage with disks or heavy cultivators or reducing the duration of maintaining loosened condition of soil during warm season and 5
ploughing fields late in autumn there is a tendency that water supplies in soil accessible to plants increase. • Shallower tillage of soil in the surface (arable) layer in autumn and winter results in lower accumulation of moisture in autumn and winter and during spring melting surplus water replenishes ground waters (through macropores) and increases drainage run-off during that period. • Reduced tillage systems do not worsen water regime, reduce nutrient leaching and are suitable as agrienvironmental measures in a region of intensive agriculture, especially in crop production farms. Practical Importance of Work According to the achieved research data the impact of tillage systems on nitrate nitrogen leaching was established. Having found out the impact of tillage systems on the physical and hydrophysical properties of soil, water supplies and nitrate nitrogen concentrations in drainage water, factors to reduce nitrate nitrogen leaching were established. This research provides a farmer with an opportunity to choose a more rational tillage system, which would reduce nitrate nitrogen leaching without reducing soil fertility. Publishing of Thesis Results The research results presented in the thesis have been already published in five articles published in the following reviewed scientific periodicals of Lithuania: the research works Water Management Engineering of the Lithuanian University of Agriculture and the Water Management Institute of the Lithuanian University of Agriculture and Agriculture of the Lithuanian Institute of Agriculture. STUDY AREAS Research objects represent the region of the Middle Lithuanian Lowland with intensive agricultural production, where annual crops are mainly cultivated and the land is tilled every year. In this region tillage technologies are changing fastest due to the increase of fuel prices and reduced or no-tillage is applied more often. Field investigations were carried out in Pikeliai trial fields of WMI LUA and Dotnuva trial plots of the Experimental Department of LIA in Kėdainiai district. The research in Pikeliai object, the Graisupis catchment not far from Dot-nuva, was started in 2000. In 1994 in this object a production drainage system of 11 ha was reconstructed and separate nine drainage systems were installed for re-search purposes, the area of which was 0,761,36 ha. (Fig. 1). 2 m deep run-off measurement wells made of ferroconcrete were installed for drainage run-off measurements, which had collector drains of small drainage systems for draining trial fields. Observation wells (piezometers) were installed in between the drains for gravitational measurements of water level. 6
During 2000-2006 three tillage systems with three replications were in-vestigated in this object: conventional deep autumn (August-September) ploughing at a depth of 2325 cm, (fields drained by drainage systems 1, 7 and 8); reduced tillage soil loosened in autumn (August-September) by heavy disks at a depth of 12-15 cm (fields drained by drainage systems 2, 5 and 6) and late (late October-early November) autumn ploughing at a depth of 2325 cm, (fields drained by drainage systems 3 and 4). Each year one kind of plants was cultivated in the entire trial plot and a crop rotation cycle applied: 2000 year barley, 2001 year barley, 2002 year rape seed, 2003 year -winter wheat, 2004year -sugar beet, 2005year -spring wheat and 2006year -spring wheat.
Fig. 1. Scheme of Pikeliai object, Experiment Department of WMI LUA The research of soil moisture and soil moisture potential in the trial field of the Experimental Department of LIA in Akademija Township was started in 2004. Three tillage systems were investigated in the field of the Experimental De-partment of LIA: conventional (deep autumn ploughing at a depth of 2325 cm (T), reduced (shallow autumn ploughing at a depth of 1416 cm) (S) and no-tillage (direct) drilling (M) (Figure 2). All trial fields was divided into smaller plots (repli-cations). Each tillage variant was replicated three times. In a separated one meter strip physical and hydro physical soil properties, soil moisture regime, capillary potential and nutrient amount in soil were established. 7
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Soil Investigations soil morphological properties a soil profile was dug out,To establish samples were taken from the main genetic layers, granulometric composition of the soil in surface (020 cm) and deeper layers (each 20 cm down to a depth of 80 cm) was established using FAO/ISRIC methodology. In both research objects the physical and hydro physical properties of soil (volumetric mass, micro- and macro pore ratio, hydraulic permeability) were ana-lysed by laboratory and field investigation methods according to routine method-ologies applied by WMI LIA. The ratio of micro- and macro pores in soil was determined by a labora-tory method analysing field and total moisture receptivity by the soil. Having filled the capillaries (micro pores) of the soil samples of unbroken structure with water field moisture receptivity was established. Respectively, having filled all pores with water the total moisture receptivity was established. The difference between the total moisture receptivity and field moisture receptivity expressed in volumetric units defined the volume of soil macro pores (the difference between field moisture receptivity expressed in volumetric units and wilting moisture is considered micro pore volume). The soil samples of unbroken structure for the analyses of hydro physical properties were taken 3 times per year: in spring (when soil moisture allows till-age) right after harvesting and in late autumn before frosts. The soil samples from the surface soil layer (down to 20 cm) were taken each 10 cm and from deeper lay-ers each 20 cm. In spring and autumn, when the soil was moist enough the sam-ples were taken from a depth down to 60 cm, when the soil was dry from a depth down to 40 cm. The analyses of soil water sorption capacity were performed in the labora-tory of the Swedish University of Agriculture. According to the methodology used there samples of unbroken soil are saturated with water and placed in a pressure chamber. The value of soil potential is determined by regulating pressure. At cer-tain pressure, when water amount in a sample settles, it is weighed and soil mois-ture is calculated. Sorption forces of soil particles are very weak at soil moisture near full saturation, however, with a decrease of moisture sorption capacity in-creases. Accordingly, the measured piezometer pressure in the case of saturation is near 0 and it increases to 107cm after the soil has dried up to the degree, which is reached when drying soil samples at 1050C temperature (absolutely dry soil). On the basis of the achieved data (having made a range of soil moisture measurements by varying pressure) the curves of the relation between capillary potential and soil moisture were drawn; they are also called soil moisture characteristic or soil capac-ity to retain water. Under field conditions the analyses of the sorption capacity of soil water were made by using a portable QUICK DRAW tensiometer. When measuring ten-siometric pressure and soil moisture by weighing method we achieved the data al-