Solute Transport Modeling under Cultivated Sandy Soils and Transient Water Regime

Abstract

Drainable lysimeters offer the possibility to integrate heterogeneous solute leaching conditions caused by row crops and transient water regime, and to conveniently measure water and solute fluxes at the drainage outlet. To compare solute leaching behavior in and around drainable lysimeters operating under a transient water regime in potato (Solanum tuberosum L.) fields, parameters of the convective lognormal transfer (CLT) function model were fitted using bromide (Br-) flux concentrations (Cf) measured in lysimeters and from Br- resident concentrations (Cr) measured in adjacent soil cores. Expected mean values Ez(I) obtained from Cr and Cf CLT parameters were equivalent and well correlated (R2 = 0.78). However, estimated median values mu of the CLT function were smaller when derived from Cr (1.05 to 1.28) compared with Cf (1.23 to 2.14). Most mu values were also smaller than previously reported values for a 30-cm reference depth, indicating that 50% of solute mass would leach more readily in these coarse sandy soils. Higher variance and dispersion of Cr compared with those of Cf could be related to a smaller sampling support (sample size/sampling area) in the case of Cr measured by soil coring, or to disruption of solute transport mechanisms in the repacked lysimeter. Retained Br- in the top soil layer after 12 to 17 cm of cumulative drainage was indicated by measured Cr. Neither CLT function simulated well residual topsoil Cr values, indicating that Br- plant cycling or preferential flow probably interfered even though tuber Br- uptake was relatively small.

Impact of potato-cereal rotations and slurry applications on nitrate leaching and nitrogen balance in sandy soils

“…Site and instrumentation are described in detail in Gasser (2000) and Gasser et al (2002). Briefly, 15 drainable lysimeters (1 m 2 surface) were installed during July and August 1995, in five fields cultivated by potato farmers of the Portneuf region located near Quebec City, Canada.…”

“…The soil physical and chemical properties measured at the beginning of the monitoring period (May 1996) were presented in detail in Gasser (2000) and Gasser et al (2002). Mean and standard deviation of selected soil properties for 15 lysimeter locations are reported in Table 2.…”

“…However, less drainage occurring during this period, solute transport dynamics and dissolution/nitrification of ammonium N fertilizers probably play a role in delaying losses during this period. From a bromide tracer application at the surface of these lysimeters, it was established that an average of 190 mm of drainage water was required to displace 50% of solute mass at the 1 m soil depth (Gasser et al 2002). Since average cumulated drainage water was generally less than 150 mm during the cropping season (Fig.…”

Drip Fertigation Regime for Potato on Sandy Soil

“…However, this method is very time-consuming and inefficient to determine drip fertigation scheduling for potato, because many multitreatment trials are needed for the different nutrient application levels: Nitrogen (N), phosphorus (P) and potassium (K) (Chawla and Narda, 2001;Darwish et al, 2006;Janat, 2007;Kaur et al, 2005;Kumar et al, 2007;Mohammad et al, 1999;Papadopoulos, 1988;Singh et al, 2004). Due to variations in water movement, spatial and temporal distribution within the soil and fertilizer application method, nutrient transport and distribution in the wetted soil volume under drip irrigation differ from those under conventional irrigation (flood, furrow and sprinkle) (Gasser et al, 2002). However, the fertilization requirement for potato is mainly determined by its biological characteristics.…”

Measured and Predicted Solute Transport in a Tile Drained Field

“…For example, Vanderborght et al (1996) installed horizontal TDR probes at different depths in a lysimeter having a 1 m deep undisturbed layered sandy soil monolith and found that m I and s I in the surface layer (7.5 cm depth) were 2.80 and 1.01, respectively. Furthermore, Gasser et al (2002) conducted a leaching study in a potato field with sandy soil and determined transfer function parameters for Br resident concentrations in the soil profile of 105 cm around the lysimeter. They reported lower m I of 1.28 and larger s I of 1.07 at 7.5 cm observed depth.…”