Modelling Water Dynamics, Transport Processes and Biogeochemical Reactions in Soil Vadose Zone

Large numbers of numerical models are nowadays available for the description of physical and chemical processes affecting water flow and solute transport in soil vadose zone. This chapter explains basic principles of water flow and solute transport modelling in soil vadose (variably saturated) zone and some of the most important processes present in it. First part deals with water dynamics in the soil, that is, soil water content, pressure head, soil porosity, and water flow. Also, some of the measurement techniques used to estimate water dynamics in soil are explained. Water retention curve and soil hydraulic properties needed for modelling are briefly discussed with the explanation of basic (i.e. most commonly used) hydraulic relationship in soil (van Genuchten equation) and water flow (Richards equation) approaches. Second part includes solute transport description in vadose zone, including processes such as advection, diffusion, dispersion, and adsorption. Basic advection‐dispersion equation is explained and also the implementation of boundary and initial conditions in the numerical model. Preferential flow is shortly discussed with the basic principles behind its occurrence and modelling in the soil vadose zone. One real case one‐dimensional (1D) example of modelling with HYDRUS software is presented in which water flow and nitrate transport is simulated on the lysimeter study. Short overview of the most widely used numerical models for simulating vadose zone processes is also presented, whereas the final part is focused on chemical speciation modelling in relatively homogeneous soil solutions using visual MINTEQ interface

Heavy Metals Accumulation in Topsoils from the Wine-growing Regions Part 2. Relationships between soil properties and extractable copper contents

The present study analyses the effects of high copper concentrations on its mobility in the soils from the wine-growing regions of the Northwestern Croatia. The aims of this study were to determine the copper distribution in vineyard soils by single extraction procedures, and to relate the total, mobile and mobilisable copper content to several chemical soil characteristics using multiple regression analysis. The total Cu concentrations were determined by an aqua regia procedure. Two other methods were used for evaluating soil available copper: DTPA extraction and calcium chloride extraction. The physical and chemical characteristics (texture, organic C, pH, CaCO3, total P, CEC) were determined as well. Both DTPA- and CaCl2-extractable copper were largely explained by the total copper contents, and they were also highly correlated to each other. It was found that the DTPA-extractable copper decreased with increasing cation exchange capacity, but concentrations of CaCl2-extractable copper mainly depend on pH

Učinci razine zaslanjenosti vode za navodnjavanje na produktivnost boba (Vicia faba L.)

In Mediterranean region where seawater intrudes porous karst matrix and salinizes soil and water resources, water used for the irrigation of crops is frequently of inadequate quality. Measuring the productivity of horticultural crops under saline conditions helps to determine whether and when to irrigate crops if water is saline, thus balance between crop water and salt stress. A greenhouse pot experiment was set to study the effects of saline irrigation water on faba bean (Vicia faba L.) biomass and yield parameters. NaCl salinity was applied in a nutrient solution as follows: NaCl0 as control (nutrient solution without added NaCl), NaCl50 (control + 50 mM NaCl), and NaCl100 (control + 100 mM NaCl). Five weeks after salinity treatment started, plant height (cm), number of lateral branches per plant, number of pods and seeds per plant, shoot weight (g), pod weight (g) and seed weight (g) were determined. Compared to control, increased irrigation water salinity statistically significantly decreased measured parameters (P<0.01), except for number of branches and pods. Faba bean productivity decreased proportionally to the irrigation water salinity level, suggesting that optimal saline agriculture management strategy can be to allow for the acceptable yield loss in order to avoid plant water stress.Na području Mediterana, gdje dolazi do prodora morske vode kroz porozni krški materijal i zaslanjivanja tala i vodnih resursa, voda koja se koristi za navodnjavanje usjeva često nije odgovarajuće kakvoće. Mjerenje produktivnosti hortikulturnih usjeva u zaslanjenim uvjetima pomaže odrediti može li se navodnjavati zaslanjenom vodom i kada, kako bi se pronašla ravnoteža između vodnog stresa usjeva i stresa soli. Postavljen je pokus u loncima u plasteniku kako bi se istražili učinci zaslanjene vode za navodnjavanje na biomasu i parametre prinosa boba (Vicia faba L.). NaCl sol je primijenjena u hranjivoj otopini kako slijedi: NaCl0 kao kontrola (hranjiva otopina bez dodanog NaCl), NaCl50 (kontrola + 50 mM NaCl), i NaCl100 (kontrola + 100 mM NaCl). Pet tjedana nakon početka tretmana zaslanjenom vodom, izmjerena je visina biljaka (cm), određen broj bočnih izdanaka, mahuna i sjemenki po biljci, masa nadzemnog dijela biljke (g), masa mahune (g) i masa sjemena (g). U usporedbi s kontrolom, povećana zaslanjenost vode za navodnjavanje statistički je značajno smanjila mjerene parametre (P<0.01), osim broja izdanaka i mahuna. Produktivnost boba smanjila se proporcionalno razini zaslanjenosti vode za navodnjavanje, sugerirajući da optimalna strategija poljoprivrednog gospodarenja u zaslanjenim uvjetima može biti dozvoljavanje prihvatljivog gubitka prinosa kako bi se izbjegao vodni stres usjeva

Agricultural Management Strategies for Countering Drought Conditions in Eastern Croatia

The occurrence of drought periods which last for several months is becoming increasingly frequent, even in regions which have not encountered them before. Agricultural production is very sensitive to drought, and in areas where such conditions were rather unexpected, it is also unprepared for limited water management. As an example, in the area of the Biđ-Bosut field located in eastern Croatia, a significant change in the agricultural soil water regime is noticed during a long-term study (2003–2018). From 2003 to 2018, the groundwater level at 4 m below the soil surface showed a decreasing trend of 6–10 cm annually, while this negative trend was even more prominent from 2014 to 2018 (18–71 cm annually). Furthermore, water level in a groundwater aquifer at 15 m below the soil surface showed a decreasing trend of 26–77 cm during 2015–2018. In accordance with the obtained results, this study proposes certain agro-hydrotechnical strategies which can be used in agricultural production to alleviate the effects of drought period. Although these management strategies are primarily described on an eastern continental Croatia example, they can also be applied in all agricultural areas with similar agroecological conditions

Comparison of Transpiration Models in Tomato Soilless Culture

A two-year greenhouse study was performed to determine the possibility of estimating the transpiration rate in hydroponically grown tomato on the basis of climate parameters. Transpiration rate, determined by the water balance method on different substrates, was compared to the transpiration rate calculated using the Penman Monteith equation. Regression analysis of the comparison of two different approaches to water consumption determination confirmed that the transpiration rate of greenhouse grown tomato for the studied area can be estimated with high accuracy (R2 > 0.95)

Strawberry Growth and Fruit Yield in a Saline Environment

Up to 20% of irrigated arable land in arid and semi-arid regions worldwide is salt-affected. The problem of salt-affected soils is also present in the Croatian Mediterranean coastal region where seawater intrudes through porous media into calcareous aquifers, mixes with freshwater and salinizes both ground and surface waters. Climatic conditions enable continuous growing of several crops throughout a year, but increasing demand for irrigation water forces the growers to utilize water of poor quality. In 2005, the effect of rising salinity levels (control, 4, 6, and 8 dS m-1) on strawberry vegetative growth and fruit yield was studied in a greenhouse experiment. Salinity treatments had a negative effect on total fresh fruit yield (29-59%), total number of fruits (24-45%), fruit size, as well as on the number of runners (23-86%) and the length of the longest runner (1.3-2.6 times). Furthermore, NaCl salinity stress accelerated leaf senescence and reduced the strawberry growing period by 12-22 days

The Influence of Drip Fertigation on Water Use Efficiency in Tomato Crop Production

The primary objective of this study was to determine the best irrigation and fertigation practice for tomato crop (Lycopersicon esculentum Mill.) in order to achieve highest yield with maximum water use efficiency (WUE). The field experiments were conducted during the period of May to September in 2002, 2003 and 2004. Five experimental treatments tested in this study included the following: the first three treatments (T1, T2, and T3) included a combination of drip irrigation and fertigation, treatment four (T4) included drip irrigation, but with conventional application of fertilizer, and the fifth treatment, (T5), included furrow irrigation practice with conventional application of fertilizer. The results of this study show that the drip fertigation treatments (T1, T2, and T3) gave significantly higher tomato yields in comparison with treatments T4 and T5, almost 24% and 39%. During three years of research treatments under drip fertigation showed almost 28% more water use efficiency in comparison with the treatment with conventional application of fertilizer and drip irrigation and 87% more than the treatment with furrow irrigation and conventional application of fertilizer. So, it is clear that the drip fertigation led to an increased yield, indicating enhanced water use efficiency