02938naa a2200313 a 450000100080000000500110000800800410001910000170006024500820007726000090015930000110016852019870017965000110216665000120217765000140218965000310220365000170223465000090225165000090226065300170226965300110228665300280229765300250232565300120235070000210236270000220238370000200240577301990242514617322004-10-15       1999    bl uuuu     u00u1 u    #d1 aNEUMAIER, N.  aMobile rain shelters for field studies on drought in soybean and other crops.  c1999  ap.576.  aThe low availability on the market and the high prices of equipment for controlling rainfall in field experiments are considerable constraints for the development of research on drought in crops. To overcome this, a system of mobile rain shelters built as an Aluminum structure covered by transparent fiberglass corrugated sheaths was development. The shelters move, at speed of 12.5 m/min, on two steel rails 22.9 m long through a toothed bar connected to 1.0 hp stationary eletric motors switched by a panel of relays linked to a rainfall sensor device. Each shelter covers an area 10 m long by 6.6m wide (66 m2). A contiguous additional area of the same size is used as parking space. The Aluminum structure is adjustable to heights of 1.3 and 2.2 m from the soil surface, allowing its use for both short crops (e.g. soybean and wheat) and tall crops (e.g. corn and sunflower). The rainfall sensor device was also developed and built with PVC tubes and connections. Internally, it has a water deposit, two drains, a float, a lever, and an eletrics wich. Externally, it has a rainfall collector (7.2m2). When the device is filled with 200 ml of water the internal float rises and the lever turns on the switch that starts up the electric motors driving the shelters to cover the plots. As the shelter reaches  the end of the rails, it activates a stop switch opening the circuit. As rainfall continues the water deposit of rainfall sensor device is kept full, and the excess water is drained throught a 3/4" drain pipe. When the rain stops, the water inside the device slowly leaks out through a smaller drain (internal of 2mm), the float descends activating another swith starting up the eletric motors in reverse mode driving the shelters to uncover the plots. The whole system has been working fine fine for two years. However, improvements can still be made in water drainage from the shelters (gutters) and in avoidance of lateral soil water infiltration from adjacent areas.  aBrazil  adrought  aequipment  ameteorological instruments  aClimatologia  aSeca  aSoja  aAbrigo movel  aBrasil  aInstrumentacao agricola  aMobile rain shelters  aSoybean1 aFARIAS, J. R. B.1 aNEPOMUCENO, A. L.1 aQUEIROGA, J. M.  tIn: WORLD SOYBEAN RESEARCH CONFERENCE, 6., 1999, Chicago. Proceedings: invited and contributed papers and posters. Chicago: University of Illinois / Soybean Research & Development Council, 1999.