04158nam a2200313 a 450000100080000000500110000800800410001910000180006024501240007826000400020230000100024250000240025252033420027665000100361865000110362865000150363965000140365465000090366865000240367765000090370165000120371065000130372265000260373565000140376165000090377565300170378465300150380165300280381615600132000-06-21       1979    bl uuuu  m   00u1 u    #d1 aWERNER, J. C.  aResponse of two species of Stylosanthes Sw. to levels of lime, phosphorus, potassium, and boron on three mineral soils.  a[S.l.]: University of Floridac1979  a205p.  aPh.D. Dissertation.  aA greenhouse experiment was conducted to study the response of stylo (Stylosanthes guianensis (Aubl.) Sw.) cv. Schofield and Caribbean stylo (Stylosanthes hamata (L.) Taub.) cv. Verano to levels of lime, P, K, and B on three Florida mineral soils: Orangeburg loamy sand (fine-loamy, siliceous, thermic Typic Paleudult; Astatula sand (hyperthermic uncoated Typic Quartzipsament; and Myakka fine sand (sandy, siliceous, hyperthermic Aeric Heric Haplaquod). The set of experimental treatments was a modified central composite in four factors each at five levels arranged in a response surface design. Before planting each pot was leached with 1 liter of distilled water to remove nitrates+nitrites+ammonium accumulated from N mineralization during incubation period. Leachate and soil samples were taken at this time. Mineralization of organic matter, pH, exchangeable Ca, extractable P, and ECEC increased with increasing levels of lime in all three soils; exchangeable H and Al, and extreactable Fe decreased. Extractable Ca and pH of all three soils were lower at harvest time than at planting time at all levels of lime. Extractable K also decreased to extremely low levels even in the treatments that received the highest rate of K. Extractable Ca and pH values were lower when the soils were grown with stylo with Caribbean stylo. Stylo yielded more than Caribbean stylo in all three soils, and their Ca concentrations were also higher. Caribbean stylo was more responsive to lime than stylo. In the Ultisol Caribbean stylo yields increased with low but decreased with higher levels. Meanwhile, lime depressed stylo yields starting from the first level. In the Entisol and  Spodosol, Caribbean stylo responded to the highest level while stylo responded only to intermediate levels and decreased at the higher levels. Decreases in pH and extractable Ca during cropping may have accounted for the higher response to lime in the Entisol and Spodosol. Each species showed a large response to P and K in all three soils. Herbage K concentrations in the treatments without or with low levels of K were very low and the plants showed distinct symptoms of K deficiency. Increasing B levels decreased stylo yield and produced distinct foliar symptoms of toxicity as B levels increased. Caribbean stylo yield was not affected, although it showed distinct symptoms of toxicity at the highest levels of B. Increasing levels of P increased N concetration of  each species. Consequently total N increased. Increasing levels of K  tended to reduce N concentrations in each species, but since increasing levels of K had larger positive effects on dry matter yields, increased total N resulted. A very low N concentration and content of each species in the unlimed Spodosol coincided with a lack of nodulation. Na intense and general chlorosis and leaf drop indicated a very acute N deficiency caused by lack of N fixation. Sodium concentrations in herbage of stylo were very low and increased very little with increasing Tevels of NaH2PO4. Conversely, the roots were very high in sodium and increased progressively with levels of NaH2PO4, indicating that stylo has a mechanism that impairs the translocation of absorbed Na to plant tops. Increasing levels of lime decreased B, Zn, Mn, and Cu concentrations in herbage of each species all three soils.  aboron  aliming  aphosphorus  apotassium  asoil  aStylosanthes hamata  aBoro  aCalagem  aFósforo  aLeguminosa Forrageira  aPotássio  aSolo  aFeed legumes  aStilosante  aStylosanthes guyanensis