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Phosphorus (P) enrichment can lead to imbalance in nutrient availability and pollution of terrestrial and aquatic ecosystems. Hence studies were carried out to investigate fractionation and sorption of P in eleven P-enriched soils collected from different agro-climatic sites in Norway. Different P fractions viz. total, organic, inorganic (easily soluble P, Fe-P, Al-P, Ca-P and occluded P), P w (water extractable), and NH 4 -lactate extractable P (P AL ) at the beginning and after the completion of the experiments varied widely among the soils studied, indicating a wide variability of P supplying capacity of these soils. Soluble P was positively correlated to Ca-P (r = 0.94; P < 0.001), P w (r = 0.87; P < 0.001), pH (r = 0.79; P < 0.01) and P AL (r = 0.79; P < 0.01), whereas it was negatively correlated with ammonium oxalate-extractable Al (Al ox ) (r = À0.68; P < 0.05). Iron-P was only moderately related to Al ox (r = 0.64; P < 0.05) and P ox (r = 0.70; P < 0.05), whereas it was not related to any of the other parameters tested. The a [a = P ox / (Fe ox + Al ox )] was highly correlated with P AL (r = 0.93; P < 0.001), pH (r = 0.87; P < 0.001), inorganic P (r = 0.80; P < 0.01) and P w (r = 0.77; P < 0.01) but moderately to total P (r = 0.71; P < 0.05). Adsorption data fitted well to the Langmuir equation for most soils. The P affinity constant (k), adsorption maximum (b) and thus maximum buffering capacity (mbc) and adsorption isotherm of P were highest in the sandy clay soil from Øsaker, which also contained high amounts of Fe, Al and clay particles and the lowest in sandy soil from Vestra˚len, which contained very high initial P AL and the lowest content of Fe, Al, silt and clay among all the soils studied. The P affinity constant (k) was correlated positively and significantly to clay content (r = 0.66; P < 0.05), whereas mbc was correlated positively and significantly to clay content (r = 0.63; P < 0.05) and ammonium oxalate-extractable Fe (Fe ox ) (r = 0.63; P < 0.05). Phosphorus desorption of the soils varied widely depending on the initial P status and texture of the soils. Phosphorus desorbed by NH 4 -lactate was many fold higher as compared to CaCl 2 in most soils.

The scope of increasing the cultivated area under forages is rather limited, because of mounting pressure on need for food and commercial crops, but there is a large demand for green and dry fodder from livestock industry. Hence, fodder production has to be increased per unit area per unit time. By practicing the de-topping in commercial grain maize we can increase the fodder production, quality and it also reduces the deficit of fodder to some extent. Reviews indicated that by de-topping of maize, there may be slight reduction in grain yield of maize but by doing it at right stage/time and at right plant height it gives highest net returns than no de-topped treatments. De-topping at 30 days after silking; removing the top 6 leaves or after physiological maturity; removing all the leaves above the cob or de-topping above 10th internode gives highest fodder yield and net returns with slight or no reduction in grain yield.