Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Previous experimental study by Sharma et al. (2012a) has generated considerable information on nitrate-nitrogen (NO3-N) leaching in onion field under furrow fertigation in arid southern New Mexico. HYDRUS (2D/3D) model was used to simulate spatial and temporal distributions of nitrate-nitrogen (NO3-N) within and below the onion root zone under conventional furrow fertigation with the urea-ammonium-nitrate liquid (UAN) fertilizer. The simulated water contents in the furrow irrigated onion field agreed well with the measurements. Simulations produced similar patterns of the measured NO3-N concentration profiles throughout the growing season. NO3-N concentrations remained higher and accumulation of NO3-N was observed within the root zone. Higher NO3-N within the root zone was dependent on the rate of the UAN fertilizer application, quantity of NO3-N removed by root uptake, and NO3-N drainage fluxes below the root zone. Simulations also suggested that NO3-N below the root zone during different growth stages remained much higher than a recommended (for drinking water) standard concentration level (10 mg L−1). This resulted in higher NO3-N drainage fluxes, particularly during the fertigation events between the establishment and vegetative growth stages. This indicates the need to apply most fertigation events at an early stage of bulb formation to provide the maximum NO3-N demands by onions and to reduce potential NO3-N leaching. The objective of this study was to create contiguous homogenous site-specific management zones based on soil physical properties using fuzzy k-means technique in a 40 ha parcel of agricultural land. Fuzzy k-means classification was used to investigate the presence of distinct classes of soil parameters in the measured data set. Based on fuzziness performance index (FPI) and modified partition entropy (MPE);, the slope of curve was shifted from steep to gradual at a class value of 4; therefore, four classes were selected to divide the entire data set. These maps not only clustered the soils with similar properties but also indicated the transition zones within a study area. Hence, these maps provided four field management zones where contrasting management strategies can be developed to achieve certain yield goals. Thre of the four classes had fine textured soils while the fourth (class 4c) had coarse textured soils. Therefore, the best water management practices could be to install an efficient irrigation system like drip irrigation instead of the current furrow irrigation system in the northwest corner of the study area (class 4c) in order to improve the current water efficiency of the crops planted in this particular area. Similarly, there is also a need to improve the irrigation system in the other fields according to the map showing all the four management classes. The project results demonstrate that Hydrus 2D model can be used to model nitrate-N dynamics in the rootzone and below it and can be effectively used to reduce nitrate-N leaching through the soil profile. The results also demonstrated the usefulness of Fuzzy k-means classification on delineating contiguous areas for better management

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Gonz�lez-Delgado, A. M. and M. K. Shukla. 2014. Transport of Nitrate and Chloride in Variably Saturated Porous Media. ASCE, Irrigation and Drainage Engineering. 140 (5): 04014006.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Mexal J. G., G. A. Picchioni, M. K. Shukla, A. L. Ulery, and W. C. Lindemann. 2014. Land application of municipal wastewater to desert ecosystems: case studies Identifying risks and opportunities. Journal of Arid Land Studies. 24-1 109-112.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Shukla M.K. and J. P. Flores Margez. 2014. Particular matter emissions due to agricultural operations in Mesilla valley New Mexico. Terra Americana. 32(3)1-5.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Adhikari P., M.K. Shukla, J. Mexal and D. Daniel. 2014. Irrigation with Treated Wastewater: Quantification of Changes in Soil Physical and Chemical Properties. Irrigation and Drainage Systems Engineering, 3(1) doi: 10.4172/2168-9768.1000117.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: S. Singh, K. Grover, S. Begna, S. Angadi, M. K. Shukla, R. Steiner and D. Auld. 2014. Physiological response of diverse origin spring Safflower genotypes to salinity. Journal of Arid Land Studies. 24: 169-174.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Margez J. P., M.K. Shukla, and S.K. Deb. 2014. Mapping of Airborne Particulate Matter Collected Using Two Sensors Along US-Mexico Border. Journal of Environment and Analytical Toxicology http://dx.doi.org/10.4172/2161-0525.1000206.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Flores A., B. Schutte, M.K. Shukla, G. Picchioni and A. Ulery. 2014. Effects of saline RO wastewater on germination of salt tolerant species. ASABE section meeting, Las Cruces, NM, April 11.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Shukla M.K. and H. Sharma. 2014. Water balance analysis and development of crop coefficient for drip irrigated chile. Soil Science Society America conference, Long Beach, CA, Nov. 2-5.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Flores A., M.K. Shukla, B. Schutte, G. Picchioni, A. Ulery, and D. Daniel. 2014. Use of concentrate from reverse osmosis for agricultural use. ASA, CSSA, SSSA annual meeting, Long Beach, CA, November 4.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Flores A., and M.K. Shukla. 2014. Pore clogging due to irrigation with RO concentrate. NM WRRI 59th annual New Mexico water conference, Santa Fe, NM, November 19.

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The timing and amount of irrigation water is critical to the optimum production of crops. Partial root drying (PRD) experiments were conducted in greenhouse to evaluate comparative effects of compensated and noncompensated (no water stress) root water uptake patterns for chile (NuMex Joe Parker; Capsicum annuum). Three drip irrigation treatments used were: (1) control (fully irrigated), (2) PRD using vertically split-root system, and (3) PRD using two-compartment or lateral split-root system. In the vertically split system, water stress was applied to top 33% of the root zone whereas in the lateral split-root system alternate wetting and drying was imposed on each compartment. The two year experiment showed that chile plants under both PRD treatments with higher root length density and deeper rooting depth could compensate for water stress by taking up more water from the water available portion of the root-soil system to sustain transpiration or photosynthetic rates. Both PRD techniques have the potential for saving water in chile production especially for water limited arid environments. Previous experimental study by Sharma et al. (2012a) has generated considerable information on nitrate–nitrogen (NO3–N) leaching in onion field under furrow fertigation in arid southern New Mexico and evaluated how the existing management practices could be improved to reduce NO3–N leaching and improve water application and N efficiencies. Numerical simulations of two–dimensional water flow and urea–ammonium–nitrate reactions and transport in the onion root zone, while considering the root water and nutrient uptakes by onion plants into account, can further improve our understanding of the dynamic nature of these processes under field conditions. The objective of the present study was to model two–dimensional NO3–N distributions in and below the onion root zone under furrow fertigation using the HYDRUS (2D/3D). The modeling approach helped us apply the HYDRUS (2D/3D) tool to be adopted in future field applications for increasing NO3–N uptake and reducing NO3–N leaching in the onion crop production system under furrow fertigation. The project results demonstrate that PRD techniques have the potential for saving water in chile production especially for water limited arid environments. The Hydrus 2D model can be used to model nitrate-N dynamics in the rootzone and below it and can be effectively used to reduce nitrate-N leaching through the soil profile. One manuscript on the objective one published while the manuscript on objective 2 is under review. In addition, the model frame-work is ready and can be replicated for any other year and crop.

Publications

• Type: Journal Articles Status: Published Year Published: 2013 Citation: Deb, S. K., M. K. Shukla, J. `im?nek, and J. G. Mexal. 2013. Evaluation of spatial and temporal root water uptake patterns of a flood-irrigated pecan tree using the HYDRUS (2D/3D) model. ASCE, Irrigation and Drainage Engineering. 139: 599-611.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Pi��n-Villarreal, A. R., A. S. Bawazir, M. K. Shukla and A. T. Hanson. 2013. Retention and transport of nitrate and ammonium in loamy sand and amended with Clinoptilolite zeolite. ASCE, Irrigation and Drainage Engineering. 139(9):755-765.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Ochoa C. G., A. G. Fernald, S. J. Guldan, V. C. Tidwell, M. K. Shukla. 2013. Shallow aquifer recharge from irrigation in a semi-arid agricultural valley in New Mexico, USA. ASCE Journal of Hydrologic Engineering. 18: 1219-1230.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Ochoa, C., S. Fernald, S. Guldan, M. K. Shukla and V. C. Tidwell. 2013. Deep percolation and water table fluctuations in response to irrigation inputs: filed observation. New Mexico Journal of Science. 46: 89-104.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Margez J.P., C. V. Cordoba, P.O. Avila, B.C. Diaz, M.K. Shukla and E.S. Sosa. 2013. Soil texture and type of irrigation water on phosphorus availability from cow manure. Terra Latinoamericana 31: 211-220.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Harnandez Escamilla, J.A., J. P. F. Margez, M.F. Ramirez, N.R. Mendoza, M.D. Rios, M.K. Shukla and D. Dubois. 2013. Material particulado dispersado al aire en areas sin asfalto en Ciudad Juarez. Ciencia en la Frontera. 11(2): 9-14.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Adhikari P., M.K. Shukla and J. Mexal. 2013. Treated wastewater application in southern New Mexico: effect on soil chemical properties and surface vegetation. New Mexico Journal of Science. 46: 105-120.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Grover, K., M.K. Shukla, S. Singh and S. Deb. 2013. Salinity in agricultural soils under organic farming system. Journal Science and Technology UACJ, Ciencia en la Frontera. 11: 11-17.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Flores J.P.M., J. Lopez, N. Assadian, D. Giovanni, Casio F.P. and M. K. Shukla. 2013. Heavy metals in oat and soil treated with lime-stabilized biosolids and reclaimed wastewater. Journal of Environment and Analytical Toxicology. http://dx.doi.org /10.4172/2161-0525.S6-001.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Nemmers S.J., A. L. Ulery and M.K. Shukla. 2013. Wastewater effluent effects on Arsenic sorption in New Mexico soils. New Mexico Journal of Science. 46: 137-148.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Sammis T., M.K. Shukla, J. Mexal, J. Wang and D. Miller. 2013. Pecan Research and Outreach in New Mexico: Logic Model Development and Change in Communication Paradigms. Journal of Higher Education Outreach and Engagement. 17(1) 27-41.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Elsadek A., M.K. Shukla, M. Bleiweiss, S. Fernald and S. Guldan. 2013. Evaluating sensitivity analysis and auto-calibration of a semi-distributed hydrological model for two semiarid watersheds of New Mexico. New Mexico Journal of Science. 46: 65-88.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Deb S.K., M.K. Shukla, P. Sharma, and J.G. Mexal. 2013. Patterns of soil water depletion in irrigated mature pecans of arid southern New Mexico. Irrigation Science. 31:69-85.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Samani A., M. Bleiweiss, D. Dubois, and M.K. Shukla. 2013. Estimation of the fractional canopy cover of pecan orchards using Landsat 5 satellite data, aerial imagery, and orchard floor photographs. International Journal of Remote Sensing. 34(16) 5937-5952.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Deb S.K., M.K. Shukla Uchanski, M.E., and Bosland, P.W. 2012. Evaluation of compensated root water uptake pattern of greenhouse drip irrigated chile. 2012 Irrigation Show & Education Conference, Agriculture Track-1, Nov. 2-6, Orlando, Florida.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Sharma H., Deb S.K., M.K. Shukla, P Bosland, B. Stringam and M. Uchanski. 2013. Chile root water uptake under partial root drying: a greenhouse drip irrigated study. 2013 Irrigation Show & Education Conference, Nov. 4-8, Austin, TX.
• Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: Shukla M.K., K. Grover and *S. Singh. 2013. Salinity in agriculture soils under organic farming system. International Conference at University of Juarez, Juarez, Mexico, March 15, 2013. (INVITED)
• Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: *Sharma H., *Deb S.K., M.K. Shukla, P Bosland, B. Stringam and M. Uchanski. 2013. Chile root water uptake under partial root drying: a greenhouse drip irrigated study. 2013 Irrigation Show & Education Conference, Nov. 4-8, Austin, TX.
• Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: *Sharma H., M.K. Shukla and *S.K. Deb. 2013. Water conservation using partial root drying for drip irrigated Chile. USCID Conference, October 22-25, Denver, Colorado. (INVITED)
• Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: *Sharma H., and M.K. Shukla. 2013. Compensated root water uptake for drip irrigated chile. Soil Science Society America Annual Conference. Nov 3-6, Tampa, FL.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: The timing and amount of irrigation water is critical to the optimum production of pecans however, there are few tools available to estimate water use compared to deep percolation below the root zone. The RZWQM2 model was compared to the daily water balance method at two flood-irrigated mature pecan orchards with different soil textures and depths to water table, in the lower Rio Grande Valley near Las Cruces, New Mexico. Total estimated and simulated DP at sandy loam Site 1 were 489.1 and 445.2 mm in 2009, and 541.5 and 465.8 mm in 2010, respectively. Thus, at Site 1, 25% to 29% of the applied water percolated below the root zone, but the model underpredicted these values by 3 to 4 percentage points. In contrast, total estimated DP at silty clay loam Site 2 was 35% to 37% of the total water and again, the model underpredicted by 4 to 5 percentage points. The shallow water table levels at Site 1 with highly permeable sandy loam soil were affected by DP following irrigation events. In contrast, the deeper water table at Site 2 was not influenced by DP. RZWQM2 model affords managers to use the model to address water management issues for optimizing crop production. Spatial variability study was conducted at West Mesa near Las Cruces, NM to identify the areas where remediation is needed and suggest sustainable management strategies to reduce the effect of treated saline and sodic wastewater application on soil environment and existing native vegetation based on the spatial variability of soil physical and chemical properties. Geostatistical software (GS+) and statistical analysis of several soil physical and chemical properties was performed. SAR was spatially correlated with Ks and sand content, Ks with BD,. Blocked kriged spatial distribution maps showed positional similarity and most of the higher chemical properties were concentrated in the northwest and southeast portion and lower near the center of the experimental field. Average SAR concentration in the northwest portion was 22.77 and a southeast portion of the field was 18.12 which were above the threshold limits (> 15) for most plants. It is necessary to change the wastewater application pattern with more wastewater application in the middle and less in the northwest and southeast part of the experimental site. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The project results demonstrate that about 25-37% of water can be lost to deep percolation. The contour maps of soil properties along with their spatial structures can be used in making better future sampling designs and management decisions in the west mesa site irrigated with treated wastewater.

Publications

• Sammis T., P. Sharma, M.K. Shukla et al. 2012. A water balance trickle irrigation scheduling model Agricultural Water Management. Agricultural Water Management Journal. http://dx.doi.org/10.1016/j.agwat.2012.06.012.
• Shukla M.K. and T. Sammis. 2012. Advanced soil physics class develops research and teaching skills. NACTA Journal. 56 (1): 2-7.
• Picchioni G., M.K. Shukla, J. Mexal, et al. 2012. Land application of treated industrial wastewater to a Chihuahuan Desert shrubland: four-year assessment of water quality and mineral deposition. Arid Land Research and Management. 26:3, 211-226.
• Sharma, P., M. K. Shukla, T. W. Sammis, R.L. Steiner and J. G. Mexal. 2012. Nitrate-Nitrogen Leaching from three Specialty Crops of New Mexico under Furrow Irrigation System. Ag Water Management. 109:71-80.
• Picchioni, G.A., J.G. Mexal, M.K. Shukla, A. Ruiz, M. Babcock, D.L. Daniel, and D.S. Rodriguez. 2012. Land Application of Treated Industrial Wastewater on a Chihuahuan Desert Shrubland: Impacts on the Natural Vegetation. Arid Land Research and Management. 26:4, 312-327.
• Sharma, P., M. K. Shukla, T. W. Sammis and P. Adhikari. 2012. Nitrate-Nitrogen Leaching from Onion Bed under Furrow and Drip Irrigation Systems. Journal of Applied and Environmental Soil Science. Vol. 2012, doi:10.1155/2012/650206.
• Deb, S. K., M. K. Shukla, and J. G. Mexal. 2012. Estimating midday leaf and stem water potentials of mature pecan trees from soil water content and climatic parameters. Hort. Sci. 47(7):907-916.
• Deb S. and M. K. Shukla. 2012. Variability of hydraulic conductivity due to multiple factors. American Journal of Environmental Science. 8(5) 489-502.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Open-canopies in mature pecan orchards have potential to modify tree microclimate and surrounding soil surface conditions, yet little is known about the root zone soil water dynamics in irrigated pecans within and outside tree canopies. Simulations were carried out using HYDRUS-1D model to quantify isothermal and thermal water fluxes in the unsaturated zone of a mature pecan orchard in Las Cruces, New Mexico, with and without root water uptake. Isothermal water flux dominated the soil water movement in bare soils immediately after irrigation, while the contribution of thermal vapor flux increased with increasing soil drying because of upward isothermal and much smaller thermal water, and vapor fluxes within 20 cm depth. In contrast, isothermal water flux was predominant throughout the under-canopy soil profile. Immediately after irrigation, trends of under-canopy actual and potential evaporation rates were similar. With the depletion of surface soil water, evaporation losses were lower and actual transpiration due to root water extraction substantially contributed to actual evapotranspiration. Relative evapotranspiration (ratio of actual to potential) correlated (P<0.05) with the pecan stem water potential. Root water uptake pattern followed the root density distribution immediately after irrigation but compensated uptake remained higher during water-stressed conditions in the top 20 cm. Estimating spatial variability of soil physical and chemical properties is a prerequisite for soil and crop-specific management. The objectives of this study were to determine the degree of spatial variability and variance structure of soil physical and chemical properties on a 40-ha agricultural field in Las Cruces, NM in order to observe any change in the variance structure due to the cropping system and also to suggest future sampling designs to make efficient management decisions. Soil samples were collected at the center of a regular grid of 50 m x 50 m and also on the grid line during Nov. 2008 and 2009 from 0-15 cm depth. The software package GS+ (Gamma Design Software, Plainwell, MI) was used to model the variance structure of various soil physical and chemical properties. The semivariograms showed that range of spatial dependence varied from 86 m (pH, 2008) to 563 m (Ks) for all measured soil properties. Cross-semivariograms showed that NO3- N and EC were spatially correlated; therefore, kriging or cokriging can be used to estimate NO3- N values throughout the growing season from easily available EC data. Correlograms with Moran's I indicated a distance of 140 m was sufficient to yield independent samples for measured soil physical and chemical properties. The kriged contour maps showed positional similarities. These contour maps of soil properties along with their spatial structures can be used in making better future sampling designs and management decisions. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The project results demonstrate that about 11% of water is lost due to vapor flow. The contour maps of soil properties along with their spatial structures can be used in making better future sampling designs and management decisions. One manuscript on each of the two objectives was published. In addition, the model frame-work is ready and both these studies can be replicated for any other year and crop.

Publications

• Deb, S. K., M. K. Shukla, and J. G. Mexal. 2011. Numerical modeling of water fluxes in the root zone of a mature pecan orchard. Soil Sci. Soc. Am. J. 75:1667-1680. Deb S.K., M.K. Shukla, P. Sharma, and J.G. Mexal. 2011. Patterns of soil water depletion in irrigated mature pecans of arid southern New Mexico. Irrigation Science. DOI: 10.1007/s00271-011-0293-1.
• Adhikari P., and M.K. Shukla. 2011. Spatial variability of electrical conductivity of desert soil irrigated with treated wastewater: Implications for irrigation management. Applied Environmental Soil Science. doi:10.1155/2011/504249.
• Adhikari P., M.K. Shukla and J. Mexal. 2011. Assessment of the soil physical and chemical properties of desert soils irrigated with treated wastewater using principle component analysis. Soil Science. 176(7):356-366.
• Gonzalez-Delgado, A. M. and M. K. Shukla. 2011. Coupled transport of nitrate and chloride in soil columns. Soil Science. 176(7):346-355.
• Gonzalez-Delgado, A. M., M. K. Shukla, A. L. Ulery, A. S. Bawazir, and P. V. Brady. 2011. Saturated hydraulic conductivity of self-sealing lining materials for desalination evaporation ponds. Desalination and Water Treatment. 29:187-195.
• Ortiz G., M.K. Shukla, J. Mexal, D. VanLeeuwen and Y. Ikemura. 2011. Physical and chemical soil properties in conventional and organic farms of southern New Mexico-a case study. Comm. Plant and Soil Ana. 42:1791-1808.
• Margez J.P.F., M. K. Shukla, and J. Wang. 2011. Particulate matter emitted by vehicle running on unpaved roads in Juarez valley of Mexico. TERRA LATINOAMERICANA. 29: 23-34.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Information on the coupled liquid water, water vapor and heat transport under arable field conditions is still limited, particularly for unsaturated soils of semi-arid and arid regions such as New Mexico. HYDRUS-1D model was applied to evaluate various transport mechanisms associated with temporal variations in water content and soil temperature in the unsaturated zone of a sandy loam furrow-irrigated field located at Leyendecker Plant Science Research Center, Las Cruces, New Mexico. The model was calibrated using measured soil water content and soil temperature at 5, 10, 20, and 50 cm depths during a 19-day period (Day of the Year (DOY) 85-DOY 103, 2009) and validated for a 31-day period (DOY 104-DOY 134, 2009). Measured soil hydraulic and thermal properties, and hourly meteorological data were used in model simulations. HYDRUS-1D simulated water contents and soil temperatures correlated well with the measured data at each depth. The total liquid water flux, comprised of isothermal and thermal liquid water, dominated the soil water movement during early periods after irrigation, while the contribution of total water vapor flux, comprised of primarily thermal and much smaller isothermal water vapor, increased with increasing soil drying. During the soil drying process, the total liquid fluxes within 15 cm depth eventually changed to water vapor near the surface. The upward total liquid and vapor fluxes decreased from 5 cm, indicating that vapor flux was much higher in the layer near soil surface. The total vapor flux in this unsaturated soil layer was approximately 10.4% of the total liquid and vapor fluxes during the simulation period. Water is a limited resource for crop production in arid and semi-arid areas. The purposes of this study were to estimate the amount and depth of water and nitrate-nitrogen (NO3-N) fronts below the rooting zone for two onion (Allium cepa L.) fields under furrow and drip irrigation systems located in the Mesilla Valley of Southern New Mexico and determine how the current best management could be improved. Soil samples were collected during the last week of each month throughout the growing season from both fields. Soil samples were analyzed for NO3-N and chloride concentration. The total amounts of N fertilizer applied to furrow and drip irrigated fields were 383 and 292 kg ha-1, and total water applied was 95 cm and 81 cm, respectively. The amount of NO3-N in the soil water estimated by chloride tracer technique was 165.9 +/- 0.97 mg L-1 (Mean +/- SE) for furrow and 66.8 +/- 4.45 mg L-1 for drip irrigated fields for the 60-200 cm depth. The NO3-N loadings below the rooting zone were 240 +/- 2.6 kg ha-1 for furrow and 79 +/- 6.9 kg ha-1 for drip irrigated fields. A leaching fraction of 0.20 +/- 0.006 was obtained from the furrow and 0.17 +/- 0.02 from drip irrigated field. The irrigation efficiencies were 80 +/- 0.60% and 83 +/- 2.0% and wet onion yields (moisture content 90%) were 45120 kg ha-1 and 50980 kg ha-1 for the furrow and drip irrigated fields, respectively. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The project results demonstrate that about 11% of water is lost due to vapor flow. Therefore measures should be undertaken to control evaporation for conserving water. Small and delayed N fertilizer application until onion bulbing starts, frequent applications of fertilizer and water preferably through drip irrigation are recommended to reduce deep percolation and increase nitrogen and water use efficiencies. Two manuscripts were written and are currently under review. In addition, the model frame-work is ready and both these studies can be replicated for any other year and any other crop.

Publications

• Sharma P., M.K. Shukla and T. Sammis. 2010. Predicting soil temperature using air temperature and soil and meteorological parameters. Applied Engineering in Agriculture. 26(1):47-58.
• Deb S.K., M. K. Shukla, and P. Sharma. 2010. Numerical analysis of coupled liquid water, water vapor, and heat transport in a sandy loam soil. The 19th World Congress of Soil Science on 'Soil Solutions for a changing a world', International Union of Soil Science, August 1-6, 2010, Brisbane, Australia. 121-124.
• Deb S.K., P. Sharma, M. K. Shukla, J. G. Mexal, T. W. Sammis, and R. St. Hilaire. 2010. Patterns of soil moisture depletion in mature pecan orchards on the Rio Grande Plains, Las Cruces. American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting, June 20-23, 2010, Pittsburgh, PA.
• Gonzalez A. and M. K. Shukla. 2010. Transport of Nitrate and Chloride in Saturated Soil Columns. The 2010 New Mexico Water Research Symposium: Resource Interdependence, August 03, 2010, Macey Center, New Mexico Tech, Socorro, New Mexico.
• Deb S., M.K. Shukla P. Sharma. 2010. Numerical Analysis of Coupled Liquid Water, Water Vapor, and Heat Transport in a Sandy Loam Soil. 19th World Congress of Soil Science. Brisbane, Australia.1-6 August.
• Deb S. and M. K. Shukla. 2010. Numerical modeling of water vapor fluxes in the unsaturated zone of mature pecan orchards in arid southern New Mexico. The 2010 International Annual Meetings, ASA, CSSA and SSSA, Oct 31-Nov 04, 2010, Long Beach, CA.
• Gonzalez A. and M. K. Shukla. 2010. Coupled Transport of Nitrate and Chloride in Unsaturated porous Media. 2010 International annual meetings, ASA-CSSA-SSSA, Oct. 31-Nov. 4, 2010, Long Beach, CA.
• Sharma, P., M. K. Shukla, and J. Mexal. 2010. Spatial variability of soil hydraulic properties in agricultural fields of Southern New Mexico: Implication on irrigation management. New Mexico Water Research Symposium held in New Mexico Tech Campus, Socorro, NM, August 3, 2010.
• Sharma, P., M. K. Shukla, J. Mexal, and T. W. Sammis. 2010. Spatial variability of soil properties in agricultural fields of Southern New Mexico. 2010 International annual meetings, ASA-CSSA-SSSA, Oct. 31-Nov. 4, 2010, Long Beach, CA.