Soil Water Storage As Affected By Soil Management.

Soil compaction can be handled either mechanically or biologically, using plant species with vigorous root systems. Besides this, both strategies can act differently on the soil water storage (SWS), which can affect the plant growth in dry seasons and the loss of water and nutrients in rainy season. Thus, the objective of this study was to determine the effect of crop rotation of cover crop species in no-till and chiseling on SWS. The experiment has been carried out since 2003 on a clayey Rhodic Nitosol, in Botucatu, state of São Paulo, Brazil, a region characterized by dry winters. The experimental design was a randomized complete block design, in a split‑plot arrangement, with four replicates. Plots consisted of the fall-winter crops, triticale (X Triticosecale) and sunflower (Helianthus annuus), and subplots of the spring managements, pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor) and sunn hemp (Crotalaria juncea), besides chiseling in 2003 and 2009. In the other years, the subplots chiseled were kept in fallow. Soybean (Glycine max) was grown in the summer. The SWS was evaluated to a depth of 0.8 m, using a capacitance probe (Diviner 2000^® - Sentek Pty Ltd., Stepney South Australia) during the winter-fall and spring season in 2012 and soybean season in 2012/2013, performing 105 assessments. For the fall-winter crops, there were differences only during the grain-filling period of fall-winter crops, coinciding with largest dry period. The triticale reduced the SWS from 360 mm to 272 mm, while the sunflower reduced the SWS from 361 mm to 314 mm. Despite larger water consumption, the yield of triticale was higher than that of the sunflower. For the spring managements, the pearl millet showed the lowest SWS, while the sunn hemp and sorghum were intermediate. The chiseling showed the highest SWS, but these differences occurred only during the last twenty days before the chemical desiccation, when the plants were large and the transpiration was high. During the soybean season, the differences among the spring managements were the same, but not statistically significant. This result suggests that the effect of spring managements over the SWS is more durable than the fall-winter crops.