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| Guimarães,Alaine Margarete; Caires,Eduardo Fávero; Silva,Karine Sato da; Rocha,José Carlos Ferreira da. |
| Chemical stratification occurs under no-till systems, including pH, considering that higher levels are formed from the soil surface towards the deeper layers. The subsoil acidity is a limiting factor of the yield. Gypsum has been suggested when subsoil acidity limits the crops root growth, i.e., when the calcium (Ca) level is low and/or the aluminum (Al) level is toxic in the subsoil layers. However, there are doubts about the more efficient methods to estimate the gypsum requirement. This study was carried out to develop numerical models to estimate the gypsum requirement in soils under no-till system by the use of Machine Learning techniques. Computational analyses of the dataset were made applying the M5'Rules algorithm, based on regression models. The... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Rule induction; Calcium; Aluminum; Subsoil acidity; Phosphogypsum. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902015000200250 |
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| Miyazawa,Mário; Pavan,Marcos A.; Franchini,Júlio C.. |
| A baixa mobilidade do calcário aplicado na superfície do solo diminui sua eficiência na redução da acidez subsuperficial. Foram estudados os efeitos de alguns resíduos orgânicos sobre a mobilidade do calcário calcítico aplicado na superfície do solo em colunas de PVC (60 cm de altura por 15 cm de diâmetro). Avaliaram-se resíduos de aveia preta, trigo, centeio, mucuna cinza e leucena na dose equivalente a 40 Mg ha-1. Adicionaram-se os resíduos vegetais e o calcário na superfície do solo e, após um programa de irrigação equivalente a 1500 mm de chuva por ano, avaliaram-se o pH e os teores de Ca, Mg, K e Al trocáveis no solo e solúveis na água efluente. O efeito do calcário sem resíduos vegetais limitou-se aos primeiros 10 cm de profundidade. Os resíduos... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Subsoil acidity; Ca leaching; Green manure. |
| Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132002000300001 |
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| Cassiolato,Marcelo E.; Meda,Anderson R.; Pavan,Marcos A.; Miyazawa,Mário; Oliveira,José C. de. |
| The low mobility of the soluble components of surface-applied lime, limits their ability to reduce subsoil acidity in variable charge soils. Laboratory experiments were conducted with brazilian Oxisol to evaluate the effect of oat extracts on the mobility of surface applied calcium in form of CaCO3. The following oat cultivars were evaluated: Argentina 5VL3, UPF 90H400-2, IAPAR 61, IA96101-b, SI 83400, EMBRAPA 29, LD 9102, FAPA 1, ER 93247, ER 90148, ER 89144, ER 93152, Alpha 94124, Alpha 94206 and Preta comum. Oat extracts and lime were applied at rates of 10 and 5 Mg ha-1, respectively. Effect of lime without plant extracts on soil acidity was limited in the upper 10 cm of the profile. Lime in the presence of oat extracts increased pH and Ca ex and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Subsoil acidity; Ca-leaching; Plant residue. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132000000500014 |
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| Ziglio,Cláudio M.; Miyazawa,Mario; Pavan,Marcos A.. |
| A falta de Ca e a presença de Al na subsuperfície do solo restringem o crescimento das raízes. A eficiência da calagem aplicada na superfície do solo na neutralização da acidez subsuperficial é limitada. Foram conduzidos experimentos de laboratório com colunas de PVC para avaliar técnicas orgânicas e inorgânicas na mobilidade do Ca em solo com carga variável. Foram conduzidos dois experimentos com sais de Ca: CaCO3, CaSO4, Ca(NO3)2, Ca-acetato e Ca-citrato, e outro com CaCO3 associado com resíduos de aveia preta, trigo e leucena. Avaliaram-se os teores de Ca trocável em solucão de KCl 1M nas profundidades de 0 a 5, 5 a 10, 10 a 20, 20 a 30, 30 a 40 e 40 a 50cm. A eficiência dos sais na mobilidade de Ca seguiu a ordem: NO3 > Acetado > Citrato > SO4... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ca-leaching; Subsoil acidity; Green manure; Plant residue. |
| Ano: 1999 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89131999000200016 |
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| Meda,Anderson R.; Pavan,Marcos A.; Cassiolato,Marcelo E.; Miyazawa,Mário. |
| Low Ca and Mg are serious limitations to crop production in sandy soils of the northwest Paraná, Brazil. Thus soil samples of an Oxisol collected in this region were packed into 30cm long columns. Dolomite lime (2.0, 0.84, 0.30, and < 0.30 mm screen) was added on soil surface, then leached with deionized water. Thereafter, the columns were dismantled and the soil cut into 5cm segments for chemical analysis. Dolomite lime increased pHCaCl2,, KCl-exchangeable Ca and Mg and residual CO3 mostly in the top surface layers. Surface dolomite lime had no effect on pH, Ca, Mg, and CO3 in the leachate, independent on the lime particle size. These results indicated that surface dolomite lime application had no effect on subsoil composition and mostly of the calcium... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Liming; Ca and Mg leaching; Subsoil acidity. |
| Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132002000200014 |
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