Geno A. Picchioni

A growth-irrigation scheduling model for wastewater use in forest production

Applying wastewater and sludge to land for remediation has been recommended by the Environmental Protection Agency (EPA) as a method to recycle nutrient and organic matter and conserve water resources. The level of sewage treatment can range from simple primary treatment using a lagoon to tertiary treatment using a standard wastewater treatment plant. Small communities are selecting primary treatment and land application as the most cost-effective way of treating municipal wastewater. Wastewater was used to irrigate an Eucalyptus camaldulensis plantation in Ojinaga, Chihuahua, Mexico. The overall objective of the research was to develop a daily growth-irrigation scheduling model (GISM) for Eucalyptus tree plantations based on the trees’ water needs with the source of irrigation water being wastewater from a lagoon sewage treatment system. A second objective was to check this model against measured growth data to determine the limitations of using a simple irrigation-scheduling model to manage the irrigation system to maximize tree growth and wood production. The GISM calculated the evapotranspiration (Et) from the volume balance soil water model and a tree biomass sub-model, based on a water use efficiency (WUE) (biomass/Et) that partitions biomass determined from Et into the component parts of leaves and stems plus branches. The water balance portion of the model computes the Et for grass growing between the trees until a closed canopy system is reached. Weather data and a soil water stress function were used to calculate Et based on calculated reference Et and crop coefficients (Kcs) for both the trees and grass scaled to nonstressed Et. The GISM model accurately modeled height and diameter growth, although, it slightly overestimated the height growth of Eucalyptus for the high irrigation treatment in the second and the third years. The GISM model was successful in predicting height and diameter growth within a 95% confidence level of the measured height and diameter of the trees under all irrigation treatments. Based on the modeled and measured data analysis, the GISM model can be a useful tool to predict tree growth and schedule irrigations for Eucalyptus tree plantations, understand the trees response to environmental and water stress, and to provide better analyses for future research efforts. The climate-driving variables (temperature and rainfall) needed by the model are readily available for any location in the world from the National Climatic Data Center (NCDC).

Chemical and Physical Properties of Chihuahuan Desert Soils Irrigated with Industrial Effluent

Land application of secondary industrial effluent to Chihuahuan Desert upland near Las Cruces, New Mexico, was designed to meet the water demand of creosote and mesquite shrubs. The major objective of this study was to assess changes in chemical and physical properties of desert soils after 4 years (2002–2005) of irrigation with secondary industrial effluent. Soil texture and bulk density (pb) did not differ between irrigated and control plots, but did so between bare ground and mesquite sites in the control and irrigated plots. Reductions in saturated hydraulic conductivity (K s ), drainable porosity (θd), and effective porosity (θe) in the upper 0–15 cm of irrigated plot soils were attributed to decline of soil structure and dispersion of clays resulting from the addition of highly sodic and alkaline effluent to irrigated plots. Although rarely significant, consistently higher electrical conductivity, sodium adsorption ratio, chloride, exchangeable sodium percentage, and Na+ in the soil profile (between 30 cm and 210 cm) at creosote and mesquite sites compared to the bare ground site suggested deeper leaching of wastewater constituents at shrub sites. Deeper leaching of wastewater constituents beneath shrubs compared to bare ground areas may be attributed to higher water inputs caused by sprinkler spray interception, and higher Ks, θd, and θe of soils beneath creosote and mesquite canopies. Continued application of industrial effluent to a Chihuahuan Desert ecosystem over the long term should consider the relative importance of canopy and intercanopy areas.

Land Application of Treated Industrial Wastewater on a Chihuahuan Desert Shrubland: Implications for Water Quality and Mineral Deposition

Land application of wastewater conserves fresh water and recycles nutrients, but little is known of its impacts on arid and semiarid landscapes. Lagoon treated saline−sodic industrial effluent was applied from 2002–2005 to a 0.4-ha Chihuahuan Desert shrubland to assess the deposition and recovery of effluent components and changes in soil quality vis-à-vis a non-irrigated area. Effluent irrigation supplied 26% of the average annual nonstressed evapotranspiration (ET) of the native shrubs [Larrea tridentata (DC.) Coville and Prosopis glandulosa Torr. var. glandulosa], and increased both soil stress factors (sodicity, salinity, and pH) and soil fertility (N, P, and K). After 3 yr, the soil saturation extract electrical conductivity (ECe) reached as high as 6.1 dS m−1 and Cl− 76 molc m−3 at 105 cm depth under irrigated L. tridentata. After 4 yr, saturation extract sodium adsorption ratio (SARe) reached 25–35 at 7.5 cm under the irrigated shrubs and intershrub spaces. There were 27 Mg ha−1 of cumulative ionic deposits to the site comprised mostly of Na+, Cl−, and CaCO3 equivalent alkalinity, with soil analysis recovering most of the deposits (>57%) except for K+ and Na+ (8% to 13%). Subsurface leaching of and P was detected within the upper 1 m soil depth after 4 yr, and a high downward mobility of Cl− revealed the potential for deeper leaching at higher N loading rates. While long-term effects on the natural vegetation are unknown, results contribute to a limited scientific database for sustainable wastewater land application in semiarid regions.

Physiologic response of six plant species grown in two contrasting soils and irrigated with brackish groundwater and RO concentrate

ABSTRACT With declining availability of fresh surface water, brackish groundwater is increasingly used for irrigation in the arid and semi-arid southwestern United States. Brackish water can be desalinated by reverse osmosis (RO) but RO results in a highly saline concentrate. Disposal of concentrate is a major problem hindering augmentation of inland desalination in arid areas. The objective of this study was to determine the effect of texture and saline water irrigation on the physiology of six species (Atriplex canescens (Pursh) Nutt., Hordeum vulgare L., Lepidium alyssoides A. Gray, Distichlis stricta (L.) Greene, Panicum virgatum L., and ×Triticosecale Wittm. ex A. Camus [Secale × Triticum]). All species were grown in two contrasting soils and irrigated with the same volume of control water (EC 0.9 dS/m), brackish groundwater (4.1 dS/m), RO concentrate (EC 8.0 dS/m). Several plant physiological measurements were made during the growing season including height, number of stem nodes, average internodal length, number of leaves, leaf length, photosynthetic rates, stomatal conductance rates, transpiration rates, leaf temperatures, stem water potential, and osmotic potential. P. virgatum was the only species that showed significant decrease in plant height and growth with texture and irrigation water salinity. Except for A. canescens and L. alyssoides, number and length of leaves decreased with increasing salinity for all species. No significant differences were observed for photosynthetic, stomatal conductance, and transpiration rates by soil texture or irrigation water salinity. Stem water potential and osmotic potential did show some significant influence by soil texture and irrigation water salinity. Based on the results, RO concentrate can be reused to grow all six species in sand; however, growth of all species showed some limitations in clay. Local reuse of RO concentrate along desert margins with regular soil and environmental quality monitoring can accelerate implementation of inland desalination for sustaining food security.

Land Application of Treated Industrial Wastewater on a Chihuahuan Desert Shrubland: Impacts on the Natural Vegetation

Impacts of wastewater land application on desert vegetation are not adequately known. In a 4-yr field study, we evaluated the effects of treated, saline−sodic industrial effluent application on the aboveground vegetation biomass and mineral accumulation of a Chihuahuan Desert shrubland. The vegetation included two shrubs, Larrea tridentata (DC.) Coville and Prosopis glandulosa Torr. var. glandulosa, and seven herbaceous species in the intershrub spaces. Early summer fruit dry weights on terminal branches of the irrigated shrubs were 3 to 14 times higher than those on the non-irrigated shrubs. The combined irrigated vegetation produced 2 Mg of additional dried biomass per ha above that of the non-irrigated plot, and contained excesses of total Kjeldahl-N (TKN) and Ca2+ equivalent to 18% of effluent N deposition and 12% of effluent Ca2+ deposition. Under irrigated and highly sodic conditions (soil sodium adsorption ratio up to 35), the herbaceous Lepidium alyssoides A. Gray var. alyssoides produced the highest biomass of all plant species. However, there was a decline in plant species diversity as L. alyssoides became dominant in the irrigated intershrub spaces. While the findings demonstrate the natural attenuation of effluent minerals by native Chihuahuan Desert vegetation, highly sodic conditions may alter the composition of the vegetation community.

Salinity an Environmental “Filter” Selecting for Plant Invasiveness? Evidence from Indigenous Lepidium alyssoides on Chihuahuan Desert Shrublands☆

ABSTRACT A better understanding of site-specific factors such as soil salinity that regulate plant invasions is needed. We conducted a 3-mo greenhouse study to evaluate the salinity responses of three local maternal sources of Lepidium alyssoides, which is an indigenous species shown to aggressively colonize disturbed shrubland sites in the southwestern United States, including those affected by high salinity and sodicity. Results indicated that there were little or no population effects on plant evapotranspiration (ET), growth, and tissue Na and Cl concentrations. Significant reductions in seedling growth and ET were largely independent of various isosmotic saline irrigation solutions that included NaCl, Na2SO4, and CaCl2, each at-0.1MPa and-0.2MPa, suggesting that ET and growth were controlled by solution osmotic potential. The combined Na and Cl concentrations in leaves were 9–10% of dry weight with no visible sign of injury. However, increasing leaf mortality and abscission as a proportion of total leaf production was observed in the high-salt treatments (-0.2 MPa), with a combined Na and Cl concentration reaching 16% with high NaCl. Under saline conditions, considerable foliage salt loads of this species could deposit high-salt litter to potentially alter a landscape to its own favor and to the detriment of other salt-sensitive species. Results of this study add to a limited quantitative database on site-specific salinity factors governing plant invasions by showing the potential for these populations to behave invasively under saline conditions and, thus, potential for soil salinity assessment to predict incipient populations. However, due to its halophytic traits and indigenous status, L. alyssoides may alternatively provide ecosystem services to salinized shrublands of the arid and semiarid southwestern United States.

Nursery Crop Growth Response to Municipal Biosolids: Species Salt and Xeric Adaptation a Key Factor?

ABSTRACT Growth responses of potted ornamental crops to municipal biosolids in the semiarid southwestern USA are not adequately known. In 10- to 11-wk greenhouse pot studies, we evaluated the effects of dried biosolids-amended growing media on four ornamental crop species: Garden chrysanthemum (Dendranthema Xgrandiflorum ‘Megan’), butterfly bush (Buddleia davidii ‘Nanho Blue’), Japanese honeysuckle (Lonicera japonica ‘Purpurea’), and blanket flower (Gaillardia Xgrandiflora ‘Goblin’). The biosolids were composted without bulking agents (100% sewage sludge) and incorporated into growing media at rates ranging from 0 to 593 kg m−3, or 0 to 72% by volume. Biosolids increased substrate pH from 5.8 to 7.2 and electrical conductivity (EC) from 2.6 to 47.3 dS m−1. Any addition of biosolids (≥30 kg m−3) reduced total plant dry matter (DM) of chrysanthemum. Conversely, shoot DM of blanket flower and butterfly bush increased by four- to five-fold at biosolids rates of 59 to 148 kg m−3 (7 to 18% by volume) with corresponding increases in shoot N and P concentrations. Biosolids rates higher than 148 kg m−3 reduced top growth of the latter two species and of Japanese honeysuckle. For all species, growth reductions with excessive biosolids rates likely resulted from osmotic stress and specific NH4 toxicity. However, based on the substantial growth stimulations at moderate biosolids rates, xeric and salt-adapted species, such as blanket flower and butterfly bush, may be ideally suited for expanding the use of highly saline biosolids at semiarid nursery production sites.

Sodium Chloride Effects on Seed Germination, Growth, and Water Use of Lepidium alyssoides, L. draba, and L. latifolium: Traits of Resistance and Implications for Invasiveness on Saline Soils

ABSTRACT In the semiarid southwestern United States, long-term drought, soil salinity, and land-use intensification have increased the risk of invasive plants that threatens landscape biodiversity. Soil-related factors that regulate plant invasions are not adequately known. We evaluated the salinity responses of three invasive plant species during a 3-mo plant growth period in a greenhouse and during a 2-wk seed germination study in the laboratory. The species included the indigenous Lepidium alyssoides A. Gray var. alyssoides (mesa pepperwort) and the exotic, invasive L. draba L. (whitetop) and L. latifolium L. (perennial pepperweed). A NaCl solution at -0.2 MPa reduced germination of L. alyssoides by ≈20% and had no effect on germination of L. draba and L. latifolium, merely delaying their mean germination time by a day or less. Reductions in seedling dry matter production and evapotranspiration (ET) were observed following irrigation with NaCl solutions at -0.1 MPa and -0.2 MPa. However, on the basis of ET and total plant dry matter production under common experimental conditions, the salt resistance of these species greatly exceeded that of salt sensitive bean (Phaseolus vulgaris L.) and equaled or exceeded that of salt-resistant cotton (Gossypium hirsutum L.). Below-ground propagating structures giving rise to clonal shoots were observed for all Lepidium spp., consistent with other reports. The results indicate that vegetative propagule pressure and relatively high resistance to salinity at germination and seedling growth stages could contribute to the invasiveness of these species under saline conditions. A broader impact of the findings is in their application to the larger diversity of invasive species to aid in the understanding of soil salinity and how it may govern plant invasions. This dataset could improve risk assessment measures to favor biodiversity in rangelands and natural ecosystems of semiarid regions.