ABSTRACT Several factors interact controlling ammonia (NH3) volatilization contributing to the variability of results reported in the literature. In the milkmaid basin of Santa Fe there is no information on nitrogen loss through NH3 volatilization from dairy cattle slurry (DCS) applied to soil. The objective of this study was to quantify NH3 volatilization from application of different rates of dairy cattle slurry in winter and summer in a soil in the central region of Santa Fe (Argentina). A field experiment was carried out and four treatments were applied. The treatments included the application of three different doses of DCS: D1 = 60 m3 ha-1, D2 = 120 m3 ha-1, D3 = 180 m3 ha-1 and a control treatment without application (D0). The experiment was conducted in summer (February) and winter (July) in a randomized complete design with two replications. The NH3 volatilization was significantly higher in the summer than in the winter. The volatilization initial rates were not affected by the DCS rates applied in the different seasons of the year. The decrease in NH3 volatilization rates was related to the season of the year. The NH3 volatilization rates decrease faster in DCS treatments compared to control. This study demonstrated that NH3 volatilization was strongly related to the season of the year and to a lesser extent with the DCS rates applied.

RESUMEN Los factores involucrados en la volatilización de amoníaco (NH3) son diversos e interactúan entre sí, lo que genera variabilidad en los resultados reportados en la literatura. En el centro de la cuenca lechera santafesina no existe información sobre las pérdidas de nitrógeno por volatilización generadas a partir de la aplicación al suelo de efluentes líquidos de tambo (ELT). El objetivo de este estudio fue cuantificar la volatilización de NH3 luego de la aplicación de diferentes dosis de efluentes líquidos de tambo en invierno y verano en un suelo de la región centro de Santa Fe (Argentina). El experimento se realizó a campo y se aplicaron cuatro tratamientos que consistieron en la aplicación de tres dosis diferentes (D1= 60 m3 ha-1, D2 = 120 m3 ha-1, D3 = 180 m3 ha-1) de ELT y un tratamiento testigo sin aplicación (D0). El experimento fue realizado en verano (febrero) y en invierno (julio) siguiendo un diseño completamente aleatorizado con dos repeticiones. La volatilización de NH3 fue significativamente mayor en verano respecto de invierno. Las tasas iniciales de volatilización de NH3 no fueron afectadas por las dosis de ELT aplicadas en las distintas estaciones del año. La disminución de las tasas de volatilización estuvo relacionada con la estación del año y decrecieron más rápido en los tratamientos con ELT comparado con el testigo. Los resultados demuestran que la volatilización de NH3 está fuertemente relacionada con la estación del año y en menor medida con la dosis de ELT aplicada.

The objective of this research was to analyze the effect of the use of plots-nighttime and liming on soil properties in a degraded Aquic Argiudoll. In a field experiment three treatments were established: a) plots-nighttime (N), b) plots-nighttime+liming (NC) and c) control without amendments (T). The pH in NC increased compared to T and N. The CIC and P increased in N and NC respect to T. CIC increased in NC respect to N. Ca ++ increased in NC respect to T and N. No differences were detected in TOC, COP and CE. The IHO was narrower in T.

El objetivo fue analizar el efecto del lote-nochero y la aplicación de carbonato de calcio (CaCO3) sobre las propiedades edáficas de un Argiudol ácuico degradado. Se evaluaron a campo tres tratamientos: a) lote-nochero (N), b) lote-nochero+aplicación de CaCO3 (NC) y c) testigo sin enmiendas (T). El pH en NC aumentó comparado con T y N. La CIC y P se incrementaron en N y NC respecto de T. Sólo la CIC aumentó en NC respecto de N. El Ca++ se incrementó en NC respecto de T y N. No se detectaron respuestas en COT, COP y CE. El IHO fue más estrecho en T.

ABSTRACT Measurements of the soil cone index are widely used to assess soil resistance to root penetration (SR) and to monitor the soil compaction status of agricultural fields. However, soil sampling for SR estimation is a rather challenging task in view of the high spatial and temporal variability of the soil. This study proposed a bootstrapping method to determine the minimum sample size required to estimate the vertical profile of mean soil cone index (CI) values at different levels of precision and confidence. For this purpose, CI data from a Typic Argiudoll under no-tillage before and after chiseling was used. A total of 151 CI profiles were recorded before and after chiseling in a 3,200 m2 (40 × 80 m) no-tillage area at sampling points distributed on a horizontal 5 × 5 m aligned grid and from the top layer to 0.40 m depth by in 0.02 m intervals. A modified bootstrap routine was developed to estimate the sampling distribution of the sample mean and medians of CI values per layer. The minimum sample size to estimate the vertical profile of mean CI values at different levels of precision and confidence was determined from data of the whole soil profile, including the autocorrelation of CI readings in the vertical direction. Tilling increased the variability of this measurement and thus the sampling efforts to achieve the same level of precision and confidence were different before and after the procedure. The standard errors of sample medians estimated by bootstrapping were higher than those corresponding to sample means. In addition, to achieve the same level of precision and confidence, the estimation of the vertical profile of mean CI values based on sample medians required more observations than based on sample means. This study shows that the viability of the bootstrap approach to determine the implications of soil variability on the sampling efforts required for an accurate estimation of the vertical distribution of resistance in soils under different managements.