Nitrate Distribution in Mojave Desert Soils

Hunter, Richard B.; Romney, E. M.; Wallace, A.

doi:10.1097/00010694-198207000-00004

Cited by 18 publications

(15 citation statements)

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“…was reduced because the roots captured substantial amounts of soluble nutrient from the lower depths of the soil. This has been observed by other workers as well (Sharma & Tongway, 1973;Hunter et al, 1982). Moreover, translocation, and deposition of clay fractions in this coarse textured soil, even to a depth of 7.5 m, has been reported for this site (Mohammadnia & Kowsar, 2003; See Figure 2).…”

Section: Resultssupporting

confidence: 88%

Changes of Selected Soil Properties in a Floodwater-Irrigated Eucalyptus Plantation in the Gareh Bygone Plain, Iran

Khanmirzaei

Kowsar

Sameni

2011

Arid Land Research and Management

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Section: Resultssupporting

confidence: 88%

Changes of Selected Soil Properties in a Floodwater-Irrigated Eucalyptus Plantation in the Gareh Bygone Plain, Iran

Khanmirzaei

Kowsar

Sameni

2011

Arid Land Research and Management

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“…Numerous authors have noted the quite high degree of spacial variability present in soil microbial populations and the constraints which this imposes on data interpretation (Parkinson 1971 ;Hunter et al 1982). An alternative approach, which would likely have reduced variability in many aspects of the present study, would have been that of bulking and sieving soil samples before respiratory analysis, following those approaches adopted by Anderson and Domsch (1978).…”

Section: Discussionmentioning

confidence: 99%

The pattern of winter respiratory response to temperature, moisture, and freeze–thaw exposure in Bouteloua gracilis dominated grassland soils of southwestern Alberta

Coxson¹,

Parkinson²

1987

Can. J. Bot.

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1987. The pattern of winter respiratory response to temperature, moisture, and freeze-thaw exposure in Bouteloua gracilis dominated grassland soils of southwestern Alberta. Can. J. Bot. 65: 1716-1725. Winter respiratory activity of soils from Bouteloua gracilis dominated grassland of southwestern Alberta was examined, both under in situ field conditions and over a matrix of defined laboratory conditions. The effect of winter thaw conditions was very pronounced on observed rates of soil surface CO, evolution. Under conditions of diurnally fluctuating air temperatures, from ca. -18 to +8OC, soil surface temperatures in early January ranged from ca. -12 to +4"C, while concurrently measured respiratory activity ranged from less than 2 to over 16 mg CO,. m-,. h-'. By early spring, soil surface heating was even more extreme as a result of the greater magnitude of midday insolation exposure, with observed mean values of CO, release ranging from less than 10 to over 60 mg CO,. m-l. h-'. Laboratory incubations showed continued, although low rates of respiratory activity in soils held at subzero temperatures, with a marked biphasic response pattern evident in Arrhenius plots of soil respiration. Predicted cumulative soil surface CO, release was estimated at 34-48 g CO,. m-,, depending on whether the effects of observed postthaw respiratory response were included. Some 55 % of overall winter soil respiratory activity in the top 8 cm of the soil profile is predicted to occur at temperatures between -4 and +4"C, with the remaining respiratory activity largely occumng at temperatures up to 15°C. This magnitude of soil surface CO, release represents between 3 and 30% of previously observed estimates of belowground root mass loss in the winter period, depending on whether this mass loss is presumed to occur over the entire winter period or mainly in early spring, coinciding with the peak period of root exudate production.COXSON, D. S., et PARKINSON, D. 1987. The pattern of winter respiratory response to temperature, moisture, and freeze-thaw exposure in Bouteloua gracilis dominated grassland soils of southwestern Alberta. Can. J. Bot. 65 : 1716-1725. L'activitC respiratoire, en hiver, des sols de prairies du sud-ouest de l'Alberta, dominks par Bouteloua gracilis, a Ct C CtudiCe in situ au champ ainsi qu'en conditions contr61ies au laboratoire. L'effet des conditions de dkgel hivernal sur les taux d'Cvolution du CO, de la surface du sol fut trks prononcC. Sous des conditions de fluctuation diurne des temperatures de l'air d'environ -18 B +8"C, les tempkratures h la surface du sol au dCbut de janvier variaient entre moins de -12 h plus de +4"C, alors que les mesures correspondantes d'activitC respiratoire ~'Ctendaient h moins de 2 jusqu'h plus de 16 mg CO, . m-,. h-'.Tat le printemps, le rkchauffement de la surface du sol Ctait m&me plus extr&me, dO i l'exposition t d s intense au soleil du midi, les valeurs moyennes observks de CO, degage s'etendant de moins de 10 B plus de 60 mg CO, . m-,. h-'. Les incubations au laboratoire ont...

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“…Heaton (1984) found concentrations of NO 3 -N up to 37 mg l −1 in groundwaters in the Kalahari, Edmunds et al (1992) reported values as large as 2.8 g l −1 in Sudan, Hunter et al (1982) found concentrations of 2 to 3 g l −1 in Arizona and similar values were found in Nevada within an aerobic profile recording 14 kyr of unsaturated zone storage (Hartsough et al 2001). Barnes et al (1992) concluded that large concentrations of NO 3 were common in groundwaters in Australia where N 2 fixation by cyanobacteria was thought to be the source.…”

Section: Introductionmentioning

confidence: 98%

Nitrogen in interstitial waters in the Sahel; Natural Baseline, Pollutant or Resource?

et al. 2005

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Nitrate in the unsaturated zone between the soil surface and the water table was studied in agroforestry Parklands in north western Senegal by examination of samples obtained by hand auger. Depending on location, water tables existed at depths between 10 and 35 m below ground. Previous studies of groundwater in this region had found that large concentrations of nitrate were unconnected with anthropogenic activity. The objective of this study was to determine whether nitrogen fixing vegetation had a role in groundwater nitrate accumulation and whether roots of trees were located deeply enough to access the nitrate. Accordingly, sample profiles were augered close to stems of nitrogen fixing trees, non-nitrogen fixing trees and also in adjacent areas that were unaffected by tree presence. These adjacent areas were typically open pasture or cultivated fields. Tree fine roots were quantified in the samples and examined for the presence of mycorrhizas. Similarly, sand/soil samples were examined and tested for the presence of nitrogen fixing rhizobia that were capable of forming functional nodules on appropriate host plants. Concentrations of nitrate were greatest in soils beneath nitrogen fixing trees and nitrate was more plentiful in profiles augered beneath nitrogen fixing crops than it was elsewhere suggesting that N-fixation was the source of the nitrate. The concentrrations of nitrate that were found in the unsaturated zone were greatly in excess of the WHO recommended limit for nitrate in drinking water. High NO 3 -N/Cl ratios confirm in situ production of nitrate, and indicate that this is a natural baseline occurrence related to N-fixation. The nitrate is moving down the profile and impacts the groundwater unless it can be intercepted by plant roots. NO 3 -N amounts in solution in the soil profile varied between 75 and 1000 kg ha −1 beneath trees and between 120 and 400 kg ha −1 in areas outwith tree crowns. Although these quantities of N occupy the lower end of the range of N values obtained in north American deserts, they comprise a considerable dryland resource where amounts of organic fertilizer are limited and where cost prohibits the use of commercial fertilizers. Roots of both nitrogen fixing and non-nitrogen fixing trees were deep enough to access the nitrate but the small amounts of available water at intermediate depths suggest that large scale uptake of nitrate will only be possible in the wetter zones located close to the water table. Shallow roots tended to be more heavily colonized by mycorrhizas than deeper roots but mycorrhizas were recovered from roots located 22 m below ground. Tree roots and rhizobia had similar patterns of distribution. They were commonest close to the soil surface, less frequent at intermediate depths and tended to increase in frequency close to the water table. * FAX No: +44 131 445 3943.

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Nitrate Distribution in Mojave Desert Soils

Cited by 18 publications

References 0 publications

Changes of Selected Soil Properties in a Floodwater-Irrigated Eucalyptus Plantation in the Gareh Bygone Plain, Iran

Changes of Selected Soil Properties in a Floodwater-Irrigated Eucalyptus Plantation in the Gareh Bygone Plain, Iran

The pattern of winter respiratory response to temperature, moisture, and freeze–thaw exposure in Bouteloua gracilis dominated grassland soils of southwestern Alberta

Nitrogen in interstitial waters in the Sahel; Natural Baseline, Pollutant or Resource?

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