@article {Muthaiya:1997:0140-1963:487,
	author = "Muthaiya V. and Felker P.",
	title = "Influence of phosphorus fertilizer and silviculture treatments on leaf and soil nitrogen and phosphorus concentrations in a mature Prosopis glandulosa (mesquite) stand",
	journal = "Journal of Arid Environments",
	volume = "35",
	number = "3",
	year = "1997",
	abstract = "<P> Due to the strong influence of phosphorus on nitrogen fixation in annual legumes, leaf N and P concentrations were examined in a mature stand of the tree legume Prosopis glandulosa . Eight years earlier application of 100 kg ha -1 P to trial plots had nearly tripled the soil P concentration compared to the control. This trial also examined the influence of understory removal and reduction in tree legume stand density (thinning) on soil and leaf N and P concentrations. Despite the nearly three-fold increase in soil P in the fertilized mesquite plots (7?2 mg kg -1 ) over the control (2?03 mg kg -1 ), neither leaf tissue P or N were greater ( p &gt;0?05) in the P-fertilized plots at either sampling date. Leaf N and P concentrations were twice as great in the spring (2?26%, 0?25%, respectively) as in the summer (1?13%, 0?12%).</P><P> There were no significant ( p &gt;0?05) treatment influences on soil N under or outside the canopy. However the mean soil N concentration of all five treatments was significantly ( P = 0?0008) greater under mesquite canopies (0?035%) than outside (0?024%). Available soil P was considerably below the 12 mg kg -1 level at which most legumes exhibit deficiencies. Soil P under the canopy was significantly correlated with summer leaf P ( r = 0?29, p = 0?02 N = 60), but not with spring leaf P ( r = 0?06, p = 0?65, N = 60). Soil P was not ( p &gt;0?05) correlated with leaf N for either spring or summer. In contrast, positive correlations were observed between N and P in greenhouse studies. Mean leaf concentrations of N (1?13%) and P (0?125%) in the summer were considerably below optimum leaf tissue values (N = 3?00%, P = 0?20%) obtained with seedlings in the greenhouse. Given the low summer leaf N and P concentrations, the lack of correlation between leaf N and P, and the very low soil P concentrations, N fixation in this system was probably considerably less than optimal.</P>",
	pages = "487-498",
	url = "http://www.ingentaconnect.com/content/ap/ae/1997/00000035/00000003/art00152",
	keyword = "Prosopis glandulosa, agroforestry, nutritional status, nitrogen fixation"
}