خيارات البحث
النتائج 81 - 90 من 142
The growth of planted trees subject to fumes from brickworks
1983
Gilbert, O.L. (Univ. Sheffield (UK))
[Objects of silviculture concerning stability and elasticity of forest ecosystems]
1983
Ulrich, B.
[Silvicultural systems in polluted stands - natural or conventional]
1983
Reemtsma, J.B.
[Consequences for forestry practice [forests and air pollution]]
1983
Sperber, G.
[Natural silviculture and its significance in controlling air pollution effects]
1983
Schuetz, J.-P.
[Silvicultural treatment of stands damaged by air pollution-possibilities and limits]
1983
Pollanschuetz, J.
[Limits and possibilities of soil amelioration [Germany, F.R.]]
1983
Gussone, H.A.
[First considerations on the causality of forest dieback [injurious environmental factors, Germany, F.R.]]
1983
Kreutzer, K.
Transport of ammonium- and nitrate-nitrogen in surface runoff from pasture as influenced by urea application النص الكامل
1983
Sharpley, A.N. | Syers, J.K. | Tillman, R.W.
The effect of a surface application of urea on the transport of N in surface runoff from permanent pasture in New Zealand was investigated under natural rainfall conditions. Maximum concentrations of NH4- N(3.6 mg l-1) and NO3-N(4.5 mg l-1) in surface runoff were attained 3 and 1 week, respectively, following urea application (60 kg N ha-1). Amounts of NH4-N, NO3-N, and total N transported in surface runoff from unfertilized (1.58, 0.52, and 4.73 kg ha-1 yr-1, respectively) and fertilized pasture (1.74, 1.09, and 8.96 kg ha-1 yr-1)were less than inputs in precipitation (2.09, 3.63, and 10.9 kg ha-1 yr-1), respectively. Amounts of NH4-N, NO3-N, and total N transported in surface runoff were only 0.3, 1.0, and 7.1 % of that applied. The mean annual concentration of NH4-N (0.9 mg l-1) in surface runoff from unfertilized pasture was above the recommended levels for drinking water (0.5 mg l-1) and the mean concentration of NO3-N (0.5 mg l-1) was greater than levels associated with accelerated cutrophication (0.3 mg l-1 ). The practicality of attaining or maintaining N concentrations in surface runoff from fertilized agricultural land below recommended levels is questioned.
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