Tillage systerns: geostatistic analysis of sorne properties of a soil

Claudia Sainato1, Nilda Arrigo1, Lidia Giuffré1, Beatriz SVidovsky1, Susana Orden1 y Marta Palma1

The spatial variability of humidity, pH, oxidable carbon, total nitrogen and available phosphorus were studied, through a geostatistic analysis,' for a Typic Argiudoll soU cultivated with maize, in plots with conventional tillage (LC) and no tillage (SO). Three different stages of the cultivation were analysed: fallow, flowering and harvest. From the semivariograms and their fitting models, carbon, nitrogen, and phosphorus were correlated with similar ranges (about 3 m), for SO and LC in fallow. Then a unique sampling is sufficient to describe the properties, measuring them every 3 m. The absence of spatial correlation for the variables in flowering would indicate the need of a more intensive sampling than the one made onthe most limiting variables. In harvest, there was correlation only in nitrogen and carbon, for LC. Moreover, these ones presented cross-correlation for LC and SO in fallow and harvest. This is probably due to the high association between nitrogen and organic material. Humidity and phosphorus had only inverse correlation in flowering, for LC. Carbon and phosphorus were positively correlated for LC.

Keywords: tillage, soU properties, geostatistics, spatial correlation, Argentina.
1 Facultad de Agronomia, Universidad de Buenos Aires. Avenida San Martin 4453 (1417). Buenos Aires, Argentina.