Uilton Pereira da Silva Júnior
Abstract:
The aim of this work is to study the rainfall partitions in three cultures under different soil managements: soya (Glycine max (L) Merrill) in no-tillage, corn (Zea Mays) in conventional tillage and brachiaria (brachiaria decumbens Stapf cv Comum) in no-tillage. The work was conducted from October 2011 to June 2012. This search was carried on in experimental area of the Federal University of Goias (UFG), campus Jataí, state of Goiás (Brazil). Pluviometers were installed above each culture, on the soil surface, between lines of each culture, in the soil body at 5 cm of soil depth and at 30 cm of soil depth. We used digital and handle pluviometers tools, with 3 (three) repetitions. Aimed calculating the partitions rainfall using datas given by pluviometers installed, based on numbers proposed by Kojac, et al. (2007). Worthed the precipitation intercepted by the canopy (Pf), the direct precipitation (Pd), the flow through the canopy (Ef), retained by the rain canopy (Rf), water saved in the deepth of until 5 cm of soil (Rs5), water saved in the deepth until 30 cm of soil (Rs30), runoff (RO) and the precipitation deep (Pp), over the total precipitation (Pt). To conclusion, the numbers of interceptation and saved by soya, corn and brachiaria canopy were low in negative stage, growing up with the development of foliar areas of farm. In corn culture, approximately 53% of precipitation fall down the soil of target way, in relation to total rain. In soya and brachiaria cases, the most part of rain was intercepted by the canopy before of fall down the soil, with numbers of 81,8% and 54,2% respectively. Understood that, for the three crops, only numbers of rain upper to 3 mm accepted dates of flow through the canopy. Corn presented 0,7% deep precipitation in contrast to total rains and 14% of runoff. The percentage of precipitation and runoff depth for soybeans were 7,2% and 3,7% respectively. To brachiaria was recorded 24% and 2,4% deep precipitation runoff. In tests conducted in the middle stages of vegetative brachiaria and corn, there were significant differences in precipitation retained at a depth of 30 cm soil depth in precipitation and runoff in relation to these crops. In tests conducted in the middle stages of vegetative brachiaria, and corn, there were significant differences in precipitation retained at a depth of 30 cm soil depth in precipitation and runoff. The brachiaria grown in no-till system, showed better water infiltration into the soil and less runoff. Analyzing these dates, it's possible to conclude about importance of maintenance of organic layer in the soil to reduce the runoff and elevating in the percentages of infiltration of soil water. Both the cultivated vegetable species, as the system of land management, were important in determining the values of rainfall partitions.
