The effect of different fertigation strategies and furrow surface treatments on plant water and nitrogen use

Furrow irrigation and fertigation systems should be designed and managed to optimize the availability of water and fertilizer to plants and minimize their losses through evaporation, deep drainage and leaching. We developed a furrow irrigation submodule for HYDRUS (2D/3D) and used it to evaluate the effects of different furrow soil surface treatments and different timings of fertigation on root water and solute uptake, deep drainage and solute leaching in a loamy soil. Numerical simulations showed that more water was available for transpiration in the treatments with plastic placed at the furrow bottom compared to the control treatments. However, more water was lost due to evaporation and less water was drained from the soil profile for these treatments. The highest and lowest root solute uptake was achieved when fertigation was applied in the middle and at the beginning of the irrigation cycle, respectively. The least amount of solute was leached from the soil profile for treatments with the plastic bottom and when fertigation was applied at the end of the irrigation cycle. The scenarios with plastic and irrigation in alternate furrows showed a reduction in transpiration and yield, more water loss due to deep drainage, and less water lost due to evaporation. However, similar crop yields were obtained for this alternate furrow strategy as for the control furrow surface treatments. When only half the water was used for irrigation in this scenario, the reduction in yield was less than 20 % compared to the control treatments, producing higher water-use efficiency

The effect of different fertigation strategies and furrow surface treatments on plant water and nitrogen use

Furrow irrigation and fertigation systems should be designed and managed to optimize the availability of water and fertilizer to plants and minimize their losses through evaporation, deep drainage and leaching. We developed a furrow irrigation submodule for HYDRUS (2D/3D) and used it to evaluate the effects of different furrow soil surface treatments and different timings of fertigation on root water and solute uptake, deep drainage and solute leaching in a loamy soil. Numerical simulations showed that more water was available for transpiration in the treatments with plastic placed at the furrow bottom compared to the control treatments. However, more water was lost due to evaporation and less water was drained from the soil profile for these treatments. The highest and lowest root solute uptake was achieved when fertigation was applied in the middle and at the beginning of the irrigation cycle, respectively. The least amount of solute was leached from the soil profile for treatments with the plastic bottom and when fertigation was applied at the end of the irrigation cycle. The scenarios with plastic and irrigation in alternate furrows showed a reduction in transpiration and yield, more water loss due to deep drainage, and less water lost due to evaporation. However, similar crop yields were obtained for this alternate furrow strategy as for the control furrow surface treatments. When only half the water was used for irrigation in this scenario, the reduction in yield was less than 20 % compared to the control treatments, producing higher water-use efficiency

absorption spectrometry

Expanded polystyrene (EPS) foam waste (white pollutant) was utilised for the synthesis of novel chelating resin i.e. EPS-N=N-alpha-Benzoin oxime (EPS-N=N-Box). The synthesised resin was characterised by FT-IR spectroscopy, elemental analysis, and thermogravimetric analysis. A selective method for the preconcentration of Pb(II) ions on EPS-N=N-Box resin packed in mini-column was developed. The sorbed Pb(II) ions were eluted with 5.0mL of 2.0molL(-1) HCl and determined by microsample injection system coupled flame atomic absorption spectrometry (MIS-FAAS). The average recovery of Pb(II) ions was achieved 95.5% at optimum parameters such as pH 7, resin amount 400mg, flow rates 1.0mLmin(-1) (of eluent) and3.0mLmin(-1) (of sample solution). The total saturation capacity of the resin, limit of detection (LOD) and limit of quantification (LOQ) of Pb(II) ions were found to be 30mgg(-1), 0.033 mu gL(-1) and 0.107 mu gL(-1), respectively with preconcentration factor of 300. The accuracy, selectivity and validation of the method was checked by analysis of sea water (BCR-403), wastewater (BCR-715) and Tibet soil (NCS DC-78302) as certified reference materials (CRMs). The proposed method was applied successfully for the trace determination of Pb(II) ions in aqueous samples

Coupled Flame Atomic Absorption Spectrometry

A Chromosorb-105 resin/1-(2-pyridylazo)-2-naphthol (PAN) system was developed for solid phase chelate extractive preconcentration of heavy metal ions. The metal ions on Chromosorb-105 resin column were eluted with 3.0 mL of 2.0 mol L-1 HNO3 and determined by microsample injection system coupled flame atomic spectrometry (MIS-FAAS) using 75.0 mu L of sample solution for single element determination. The influence of pH, resin amount, reagent amount, flow rate and volume of eluent and sample solution was optimized. The quantitative recoveries (>= 95%) of Fe(III), Zn(II), Cu(II) and Pb(II) ions were achieved at pH 9; resin amount, 700 mg; reagent amount, 6.0 mu mol; flow rate of eluent and sample solution, 1.0 mL min(-1) and 5.0 mL min(-1), respectively. The limit of detection and limit of quantification of understudied analytes were found to be 0.17-1.74 mu g L-1 and 0.40-2.98 mu g L-1, respectively with preconcentration factor of 150-300. The proposed method was validated by analysis of waste water (BCR-715) as a certified reference material. The method was applied successfully for ultratrace determination of studied metal ions in tap water and hot spring water samples

Steady Flow from an Array of Subsurface Emitters: Kornev’s Irrigation Technology and Kidder’s Free Boundary Problems Revisited

Kornev’s (Subsurface irrigation, Selhozgiz, Moscow-Leningrad, 1935) subsurface irrigation with a periodic array of emitting porous pipes is analytically modeled as a steady potential Darcian flow from a line source generating a phreatic surface. The hodograph method is used. The complex potential strip is mapped onto the triangle of the inverted hodograph. An analogy with the Deemter (Theoretische en numerieke behandeling van ontwaterings-en infiltratie stromings problemen (in Dutch). Theoretical and numerical treatment of flow problems connected to drainage and irrigation. Ph.D. dissertation, Delft University of Technology, 1950) drainage problem and Kidder (J Appl Phys 27(8):867–869, 1956) free-surface flow toward an array of oil wells underlain by a “wavy” oil–water interface is drawn. For a half-period of Kornev’s flow, the “wavy” phreatic surface has an inflection point. The “waviness” of the phreatic surface is controlled by the spacing between emitters, the strength of line sources, and the pipe pressure and radius. Numerical modeling with HYDRUS involved two factors which constrained the saturated–unsaturated flow: the positive pressure head at the outlet of the modeled domain and lateral no-flow boundaries, with a qualitative corroboration of analytical solutions for potential (fully saturated) and purely unsaturated flows. HYDRUS is also applied to a generalized Philip’s regime of an unsaturated flow past a subterranean hole, which is impermeable at its top and leaks at the bottom