03803nam a2200769 a 450000100080000000500110000800800410001910000180006024500650007826000910014330000100023452019220024465000120216665000160217865000110219465000140220565000090221965000110222865000150223965000150225465000100226965000160227965000100229565000090230565000170231465000170233165000160234865000230236465000130238765000110240065000130241165000090242465000220243365000090245565000120246465300210247665300140249765300230251165300090253465300130254365300240255665300170258065300130259765300240261065300260263465300180266065300180267865300190269665300160271565300130273165300260274465300100277065300240278065300260280465300120283065300130284265300090285565300250286465300360288965300100292565300180293565300130295365300140296665300080298065300230298865300220301116888532015-03-26       1988    bl uuuu      00u1 u    #d1 aRAIJ, B. van.  aGesso agricola na melhoria do ambiente radicular no subsolo.  aSão Paulo: Associação Nacional para Difusao de Adubos e Corretivos Agrícolasc1988  a88 p.  aThis is a review on the use of gypsum as a subsoil ameliorator. Gypsum is a byproduct of the phosphoric acid production that is being recommended as subsoil amendment, aiming to improve deep rooting of crops. However, there is still controversy about its use for this purpose. Large areas of brazilian soils have acid subsoils, with low calcium and high aluminum contents, conditions that constitute chemical bariers for root penetration. The harmful effect of aluminm on root development is well known. Furthermore, the presence of calcium in the root envrironment is essential since this element is not translocated from upper to other parts of the plants. Gypsum, or calcium sulfate, is a soluble salt that, unlike limestone, penetrtes into the subsoil. The most direct effect is an increase in calcium, which provides a decrease of aluminum saturation by a dilution effect. However, several papers report an effect of gypsum in reducing exchangeable aluminum. Possible rasons for this are discussed. Studies in soil solutions and nutrient solutions containing aluminum have shown that aluminum activities present negative relations with root development. On the other hand, gypsum reduces aluminum activity and as such improves root development. Field trials have shown the effect of surface applied gypsum in deepening the roots of cultivated plants in acid subsoils. In some cases this leads to water and nitrate uptake from deeper soil layers. There are also reports of gypsum improving physical properties of acid subsoils. Several experiments show positive effects of gypsum in the increase of yields. However, in some cases a possible effect of sulphur as a nutrient makes it impossible to isolate the effect of gypsum as a subsoil amendment. There are still no criteria available for when and how much gypsum to apply on acid soils. Care should be taken to avoid leaching losses of magnesium and potassium.  aacidity  aagriculture  agypsum  anutrition  asoil  aAcidez  aAdsorção  aAdubação  aAdubo  aAgricultura  aGesso  aÍon  aLixiviação  aMelhoramento  aNitrogênio  aNutrição Vegetal  aPesquisa  aPlanta  aQuímica  aRaiz  aSistema Radicular  aSolo  aSubsolo  aAdubacao mineral  aAgrícola  aAmbiente radicular  aANDA  aChemical  aChemistry propriety  aComposição  aCorrecao  aCorreção de solos  aCorretivos agrícolas  aFertilizantes  aFertilization  aGesso agricola  aImprovement  aMelhoria  aMineral fertilization  aPlant  aPropriedade quimica  aPropriedades quimicas  aRelacao  aRelation  aRoot  aRooting amelioration  aSoil physicochemical properties  aSolos  aSolos ácidos  aSubsoils  aSubstrate  aUso  aUso na agricultura  aVegetal nutrition