Guillermo Millán

Uso de clinoptilolita como un vehículo de fertilizantes nitrogenados en un suelo de la región Pampeana de Argentina

G. Millan, F. Agosto, M. Vazquez, L. Botto, L. Lombardi, and L. Juan. 2008. Use of clinoptilolite as a carrier for nitrogen fertilizers in soils of the Pampean regions of Argentina. Cien. Inv. Agr. 35(3):293-302. The properties of clinoptilolite related to cationic exchange and ionic selectivity have motivated us to study its application for agronomic purposes. The high potential of the clinoptilolite has been demonstrated as a vehicle for nitrogen fertilizers, with the aims of decreasing negative impacts on the environment and increasing fertilizer effi ciency. The objective of this study was to evaluate the effects of an exchanged form, clinoptiloliteNH 4 , and an occluded form, clinoptilolite-urea, of nitrogen fertilizer relative to commercial urea on dry matter and the nitrogen uptake effi ciency of Lolium multifl orum under controlled conditions. Lolium multifl orum, sowed in a sandy loam soil, was fertilized with 0, 60, 120, and 180 kg·ha -1 of nitrogen. Yield increased considerably and nitrogen uptake effi ciency was enhanced when clinoptilolite-NH 4 was used, possibly due to its ability to retain and slowly liberate NH 4 + ions. This effect produces time differences in nitrogen disponibility in relation to urea, making the nitrogen available for a longer time for the plant. The clinoptilolite-urea treatments reduced yields signifi cantly in comparison with urea applications only at the lowest dose. In addition, the nitrogen uptake effi ciency was always lower than the other treatments. This behavior is related to the fact that nitrogen liberation dynamics of the occluded form are much slower than for the ionic one.

Sustentabilidad del riego complementario en suelos Udipsament Típico y Hapludol Entico de Argentina

The complementary irrigation with high level of sodium in water leads to dispersive processes that deteriorate the porous space and therefore, other related properties. This could take place with low to medium levels of SAR of water, in coarse soil in which the illite is predominant in the clay fraction. It is hypothesized that irrigation may cause dispersive states in soils of medium to coarse texture under these circumstances, even with water containing low to medium levels of sodium and during short periods of use, compromising the sustainability of land production systems in the short term. The aim of this study was to evaluate the degree of susceptibility to dispersion and the effect on the soil water retention and its hydraulic properties of two irrigated soils, Typic Udipsament and Entic Hapludol, respectively, in the Center-East and NortH-West of Buenos Aires Province, Argentina. The soil water retention and the Atterbergs limits were higher under irrigated conditions in Typic Udipsament. The hydraulic conductivity decreased and the dispersion index was higher in the situation of irrigation in both soils. These results suggest the non sustainability of irrigation system evaluated.