Êste trabalho suscinto sôbre os solos do Estado de São Paulo, é o resultado de 15 anos de estudos. Foram feitos nesse espaço de tempo, mais de 80.000 km de excursões pelo Estado ; coletados cêrca de 700 perfis de solo. com suas várias camadas e compreendendo profundidades entre 1,5 e 5,0 m* Foram tomadas mais de 20.000 amostras superficiais (até 40 cm) de solo ; mais de 4.000 amostras de rochas e cêrca de 6.000 fotografias. A superfície estudada, envolve cêrca de 24.700.000 ha e está situada entre as latitudes sul de 19°50' e 25°10' e entre as longitudes (seg. Greenwich) de 44°10' e 53°10'. As altitudes variam entre 3 e 1.700 m acima do nível do mar. Neste trabalho básico, inicial, dividimos o Estado em 10 grandes tipos de solo que se acham bastante relacionados com a petrologia em geral. A descrição dêsses 10 grandes tipos, segue a ordem cronológica decrescente, segundo as formações geológicas. Começamos pelos solos provenientes de rochas arcaicas, tais como gnaisses, granitos, etc. Damos, em geral, as características físicas e químicas, assim como geologia e análise mineralógica das frações : areia fina e areia grossa, dêsses grandes tipos de solo. No trabalho são mencionadas as áreas de cada tipo de solo existente no Estado de São Paulo, as culturas principais e a vegetação nativa. Comentam-se, também rapidamente, a erodibilidade desses solos e as suas características morfológicas. Incluem-se também fotografias típicas dos principais tipos de solo, bem como três mapas, o primeiro mostrando os caminhos principais percorridos nas excursões ; o segundo, os locais de retirada de amostras e o terceiro, o mapa dos 10 grandes tipos de solo do Estado de São Paulo.

The main soil types of the State of São Paulo, Brazil, were studied during the last 15 years and their general description is presented in this paper. Over 80,000 km of field excursions were made in order to collect approximately 4,000 rock samples, 700 profiles from depths varying from 1.5 to 5.0 m, 20,000 shallow samples and about 6,000 photographs. The soil types studiel cover an area of 24,700,000 ha, located between the latitudes 19° 50' and 25° 10' South, and the longitudes 44° 10' and 53° 10' West (Greenwich), the altitude varying from 3m to 1,700 m above sea level. For this area the temperature range in the dry winter season (May to July) is from 0° to 25°C and in the rainy summer months (November to February), from 18° to 30°C. The rainfail varies from 2,000 to 3,000 mm (along the cost) and from 1,000 to 1,800 mm in the plateau. The following ten main soil types were described : massapé salmourão, devoniano, glacial, corumbataí, arenito Botucatú, roxa legítima, arenito Baurú, terciário, baixadas, and roxa misturada, and their locations are given in fig. 3. For the ten soil types, determination of physical and chemical properties were made and presented in tables 1 to 14. General information is also given on the specific area, geological origin, topography, native vegetation, and main crops grown in each one of the soils studied.

The present paper reports the results of general studies undertaken to determine the relative importance of soil moisture and light on symptom expression of the tristeza disease. It also includes data on the effects of the disease on transpiration and chemical composition of infected plants and records the results of attempts to inactivate the tristeza virus in budwood by means of hot water and chemical treatments. In the present tests, using potted plants, tristeza disease symptoms were observed to occur eight to ten weeks after inoculation on plants maintained in standing water and on those having a daily application of 200cc of water. In contrast to this relatively rapid and positive symptom expression, it required 28 weeks before definite advanced tristeza disease symptoms were recognized on the inoculated plants given only 50cc of water daily. Under continuous heavy shade conditions the healthy and inoculated plants showed practically no growth and no tristeza disease symptoms. The growth of the healthy plants increased with the increase in periods (6, 10, and 14 hrs) of exposure to daylight while the inoculated plants grew as well as the healthy plants for the first month they subsequently practically ceased growth. The results of the tests on the influence of light and soil moisture show that conditions favorable for rapid plant growth also favor early symptom expression of the disease and that stunting of the plant is one the principal characteristics of the tristeza disease. The data obtained from the transpiration studies show that under the controlled test conditions the transpiration of the healthy plants was two and a half times greater than that of the tristeza diseased plants. The study of chemical composition of the plants indicated that there were some differences in the percentages of CaO and Na(2)0 in the leaves and stems of diseased and healthy plants. The data also indicate that, although the differences in the amount of chemicals present in the root systems of diseased and healthy plants were comparatively small, in all cases except for MgO the quantities were larger in the healthy than in the diseased roots. Under field conditions, nutritional deficiency symptoms have been associated with initial tristeza disease symptoms following plant inoculations. Early tests with applications of minor elements indicated some beneficial effects from applications of zinc sulphate. Under controlled conditions in the screenhouse, however, no beneficial effects were obtained from spray applications of zinc sulphate on inoculated plants. Attempts to inactivate the tristeza virus in budwood sticks that were immersed in hot water were ineffective at the four different temperatures and fourteen exposure periods tested. The results obtained suggest that the thermal-death-point of the virus is probably higher than that of the living cells of the budwood, and that treatment by hot water does not appear to be a feasible method for inactivation of the virus in living budwood. Chemical inactivation of the tristeza virus was tried using nine different chemicals at four dilutions for each. Under the conditions of the tests none of the chemicals employed appeared to have any inhibiting effect on the tristeza virus.

Para determinar as quantidades de elementos minerais do solo, disponíveis às plantas, pode-se lançar mão de métodos biológicos, dentre os quais se destaca o de Neubauer e Schneider. Êste método tem sido bastante empregado para solos de clima temperado. Pouco se sabe, porém, de seus resultados para os solos tropicais e subtropicais. A fim de avaliar a sua eficácia, para os nossos solos, efetuou-se uma série de experiências, cujos resultados constituem o objeto do presente trabalho. O método Neubauer foi aplicado para determinação do potássio, tendo-se utilizado o centeio e o arroz, em amostras dos quatro principais tipos de solos do Estado de São Paulo, quais sejam : Arenito Bauru, Massapé-salmourão, Terra roxa legítima e Solo humoso de baixada. Os resultados, obtidos foram comparados com os teores trocáveis de potássio, obtidos por análise química direta. Utilizando o centeio, verificou-se que a extração do potássio trocável, pela planta, variou de 83 a 114% no Arenito Bauru, de 30% a 81% no Massapé-salmourão, de 22 a 38% na Terra roxa legítima e de 52 a 84% no Solo humoso de baixada. Nos casos em que se empregou o arroz, as extrações variaram de 68 a 107% no Arenito Bauru, de 52 a 147% no Massapé-salmourão, de 4 a 76% na Terra roxa legítima e de 72 a 122% no Solo humoso de baixada. Os valores superiores a 100% significam que a planta extraiu parte do potássio, numa forma mais fixa que a "trocável". Os dados mostram que o arroz, de modo geral, apresenta uma capacidade de extração do potássio maior que o centeio. Dentre os 35 resultados médios obtidos com o centeio, em apenas 2 dêles houve uma absorção superior a 24 mg de K2O, limite êsse considerado por Neubauer e Schneider como indicador de um solo suficientemente provido de potássio. De conformidade com êsse método, 33 dos 35 resultados obtidos correspondem a solos que necessitariam de adubação potássica, fato êsse que não está de acôrdo com o que a experimentação de campo tem concluído para as diferentes culturas no Estado de São Paulo.

In order to determine the quantities of rnineral elements in soils that are available to plants, biological methods of measurements such as that described by Neubauer and Schneider, have been used. This particular method has been widely employed for study of soils of temperate climates. However, very little was known as to the application and value of this biological method for study of tropical and subtropical soils. The purpose of the experiments described in this paper was evaluate the efficiency of the Neubauer method, using rye and rice plants, for determining available potassium in samples of the four principal soil types of the State of São Paulo. The soil types studied were Arenito Bauru, Massapé-salmourão, Terra roxa legítima and a Humus soil. The Arenito Bauru soil is a sand soil, with 50 - 60% of sand (> 0,2 mm and < 2 mm) and 2 - 10% of clay (< 0,002 mm). The Massapé-salmourão soil is a soil type with 30 - 50% of sand, 20 - 30% of clay and it generally has micas as primary mineral. The Terra roxa legítima soil is a soil which contains 10 - 20% of sand, 35 - 40% of clay and it is originated from basalts. The Humus soil presents a variable composition with a high content of organic matter. The results obtained from the biological tests were compared with the amounts of exchangeable potassium determined by chemical analysis. When rye was used as a test plant it was found that the relative amount of potassium extracted by the plants varied from 83 to 114% in Arenito Bauru, 30 to 81% in Massapé salmourão, 22 to 84% in Humus soil. In the tests where rice plants were used the amounts of available potassium extracted varied from 68 to 107% in Arenito Bauru, 52 to 147% in Massapé salmourão, 4 to 76% in Terra roxa legítima and from 72 to 122% in Humus soil. The values greater than 100% signify that the test plant extracted a portion of the fixed potassium not exchangeable. These data show that the rice plants in general had a greater capacity for extraction of potassium than did rye plants. Within the 35 average results obtained from measurements with rye plants only 2 were found to have absorbed more than 24 mg of K2O. This amount of potassium was considered by Neubauer and Schneider, to indicate that the soil is provided with sufficient potassium. The results from the tests using the biological method then indicate that in 33 out of 35 cases studied the soils lacked potassium. This, however, is contrary to results obtained from field experiments on these soils.

A retenção de água pelo solo se deve exclusivamente a fôrças capilares. Tôda divisão da água do solo é convencional. Quando se utiliza a equação y = xT / x + qT no estudo de processos que tendem para um valor final, a velocidade do fenômeno é dada por 1/q. Ê possível calcular para os solos do Estado de São Paulo a Umidade de murchamento por meio da Umidade equivalente. U. mu. = 0,68 U.Eq. Não se pode, em geral, aplicar com sucesso as fórmulas de Vageler e Alten para o cálculo do Hy em função dos trocáveis. O Hy do solo não se altera fazendo variar o tempo de secagem na estufa (105° - 110° C) antes da determinação. Os valores máximos dos dados referentes à água do solo foram encontrados na terra roxa legítima e os mínimos no Arenito Botucatu.

The retention of moisture by soil is conditioned exclusively by capillary forces. Any division of soil water is merely conventional. Using the formula y = xT / x + qT to compute the final value of a process, it is important to note that the velocity of the phenomenon is given by 1/q • For the major soil types of the State of São Paulo it is possible to calculate the wilting point by means of the moisture equivalent using the formula Wp. = 0,68 M.Eq. In general, the formulae of Vageler and Alten for computing hygroscopicity by means of exchangeable-ions are inadequate. Different periods of exposure of soils to temperatures of 105° - 110°C. before determinations are made do not exert a pronounced influence on hygroscopicity. The highest values for water-holding capacity were obtained in the terra roxa legítima and the lowest in the Botucatu sandstone.

Entre os métodos puramente químicos para a dosagem de cloretos no solo, tais como gravimétricos e volumétricos e os baseados em processos físico-químicos, tais como nefelométricos, colorimétricos e eletrométricos escolhemos por mais simples e exato, o eletro-titrométrico, ideado por Best (2). Foi estudada a técnica mais razoável e perfeita para a extração dos cloretos do solo e em seguida sua titulação. Como meio de extração escolhemos a água destilada, fazendo-a percolar por uma camada de solo. A relação entre solo e água foi de 1 :4. isto é, 50 gr de solo (terra fina) e 200 ml de água destilada. As dosagens tornaram-se, assim, bastante exatas e a duração do eletrodo de AgCl chegou a funcionar muito bem ainda depois de 1000 titulações. Isto não aconteceria se se usasse xima suspensão grosseira de solo para proceder à titulação. Consegue-se, com essa técnica, dosar cloretos, sem dificuldades, em 50 amostras de solo por dia. Conseguimos, assim, dosar cloretos em mais de mil amostras de solo de todo o Estado de São Paulo. Vimos que, no geral, o teor em cloretos é baixo, oscilando entre 0,2 e 2 mg de Cl~ por 100 gr de solo. Em algumas baixadas, sem circulação de água, encontramos até 20 mg por 100 gr de solo. Torna-se claro, pois, não possuirmos casos de solos ricos em sais (cloretos) que fossem prejudiciais à agricultura. Em muitos casos evidenciou-se grande pobresa em iônio Cl-, sendo recomendável mesmo a adição de cloretos nas adubações para verificar seus efeitos. Entre estes solos podemos citar a nossa terra-roxa-legítima. Estampamos série elevada de análises, apresentando o teor em Cl- no solo pág. . .) assim como um mapa do Estado de São Paulo, que esclarece o local de onde foram tomadas as amostras.

Among the methods purely chemical, used for the determinations of chlorides in the soil, such as gravimetric and volumetric ones and those based on physico-chemical procedures, such as the nefelometric, colorimetric and electrometric ones, we chose on account of being the simplest and most accurate the electro-titrometric method indea-lized by Best (2). It was studied the most reasonable and most perfect technique for the extraction of the chlorides out of the soil and afterwards their titulation. As a means of extraction we chose the distilled water making it percolate through a layer of soil. The ratio between soil and water was 1:4. i. e. 50 g of soil (fine soil) and 200 ml of distilled water. The determinations became thus very accurate and the duration of the electrode of AgCl worked out very well even after 1000 titulations. This will not happen if a rough suspension of soil to make the titulation is used. By this technique it is possible to determine the chlorides without difficulty in 50 soil samples per day. We were able, by this way, to determine chlorides in more than one thousand soil samples of the whole State of S. Paulo. We saw that, in general, the percentage of chlorides is low, ranging between 0.2 and 2 mg of Cl- per 100 grams of soil. In some low lands without circulation of water, we even found 20 mg per 100 grms of soil. So it became evident that we have no cases of soils rich in salts (chlorides) injurious to agriculture. In many cases it became evident that soils were very poor in Ionius Cl- and the addition of chlorides to the manuring was even recommended in order to examine their effects. At the end of our paper we add a great number of analyses showing the percentage of Cl- in the soil, as well as a map of the State with a view to indicate the localization of the samples.

In the beginning of this work a brief idea was given on what is understood as "clay", on the scientific methods applied to the study of the matter "clay" as well as on its conception with regard to the edaphic studies. A description is given of the methods of total and natural mechanical analyses which were employed in the agro-geological Department. The work is illustrated by a graphic showing the fractions of the mechanical analysis of the chief great soil types of the State of São Paulo. The fraction clay is then studied by chemical way in the following sequence : 1.° total chemical analysis, 2.° partial chemical analysis, 3.° chemical analysis of the Helmholz layer and 4.° study of the fixation of the ion Ca+ + in the already mentioned Helmholz layer. The first analysis separates and attacks the hydrated aluminium silicates, the hydrated oxyds of iron and aluminium, manganese, etc. In this analysis the relationship between silica and sesquioxyds was determined. The second type of attack or chemical analysis does not affect the hydrated silicates of aluminium, all others go in dissolution. In this analysis were determined chiefly the sesquioxyds in their free form in the clay complex. For the study of the Helmholz layer, i.e. the determination of changeable ions, solutes of NH4Cl N/l, HNO3 N/5, KCl N/l, etc. were used, percolation of these liquids being made through a layer of air dried soil. The relationship between soil and liquid was always 1:10. In this analysis, principally the cations K+, Ca++, Mg++, Al+ + +, H+ etc. were determined. With such determinations the calculations of the following values were obtained: S = sum of the changeable bases in ME; T = total value in ME of the sorptive power of the complex in each 100 g dried soil at 110° C. and V = percentage of saturation of the complexes with bases. Finally, the qualitative radiographic analysis of the fraction clay was carried out by means of the Debye-Scherrer-Hull method. For these studies the Siemens-Berlin apparatus was used, the transformer of which runs with all0-220 volts 60-cycle alternating current. The bulb has a copper anti-cathode and is fed by a current of 13 m.A. of intensity and the difference of potential is of 30,000, 35,000 and 47,000 volts. The flash of X-rays goes through the nickel filter in order to free it of the b irradiations which are deleterious. In this way, inciding vertically on the preparation, radiations CuK a with l = 1,539 A are obtained. The sensible film used was a Lawe-Film-Agfa, with an exposure going from 11/2 to 2 hours with 35,000 V. The chassis has a diameter of 57 mm. More than 500 radiographs of soil samples were taken, of those proceding from all districts of the State, 79 of which are presented in the present work. With this material the different constituents of the clay minerals contained in our soils were known. Thus, in the soils over the Archean geological formation, kaolinite is represented most frequently and abundantly ; the hydrargillite also appears commonly. The soils over the Glacial formation contain the same representatives and oscillations as those just mentioned. In the Corum-batai formation, quartz is the most important constituent. The Botucatu formation (lava) is that which gave origin to our legitimate red soils ; the mineralogical clay constituents of these soils are : 1.° large amount of hydrated oxyds of iron up to 35% of Fe2O3 for each 100 g of soil at 110° C. ; 2.° hydrargillite and 3.° kaolinite. The amount of the latter in the clay complex ranges between 9 and 25%. The sandy soils existing in the geological formations of lower and upper Baurú bear in their clays the following mineralogical constituents : 1.° kaolinite, 2.° montmorrillonitic type (on the upper Baurú only), 3.° hydrargillite (more common on the lower Baurú) and 4.° quartz, generally, in small percentages. These researches made it evident that the constituents of the clay fraction of our soils commonly have a small sorptive power related to the cations; it follows hence that they do not show a great power of retention of manure with the exception of the montmorrillonitic type.

The present work is a study of Vageler's formula y =x.S/ x+y.S for the determination of the final value of the reaction of the cation change in the sorptive complex of the soil. The author took the changeable H+ of the soil as a cation to be examined. Samples studied by the author belong to a chain (a series of soil profiles with 5 horizons each) taken from the original red soil ("terra roxa") of the Ribeirão-Preto Experiment Station. In these samples, as a rule, H+ changed could be considered = T - S, because the Al changed, as far as it existed, was traced in very low percentage, as can be seen in table I. For the determination of T - S, the author used a solution of (CH3COO)2Ca N/l (normal calcium acetate). As a mean of extraction, the percolation of the solution of calcium aceta te through a layer of soil was used instead of the shaking method. From what has been pointed out, it may be concluded that the application of the Vageler formula for the determination of the final value of this reaction is correct and of great advantage. A great amount of material and time is also saved. Besides, the percolation in this kind of work offers a great advantage over the shaking method, consisting of the extraction of changeable ions from the sorptive complex of soil. It has also been observed that the index T - S in this kind of soil is affected by the topography and shows that the more the soil is percolated by water the larger will be the above mentioned index. It has also become evident that organic matter does not contribute in a great extent to the variation of the index T - S.