O presente trabalho relata os dados obtidos sôbre a concentração e a quantidade de macronutritntes, N, P, K, Ca, Mg e S no tronco, ramos, fôlhas e frutos do cafeeiro, Coffea arabica, L, variedade mundo novo [(B. Rodr.) Choussy], aos dez anos de idade e crescendo em solo latossólico da Escola Superior de Agricultura "Luiz de Queiroz", em Piracicaba. São apresentados também os dados obtidos nas mesmas condições, sôbre o pêso de diversas partes (tronco, ramos, fôlhas e frutos) do cafeeiro.

This paper describes the data concerning the weight of the trunk branches and leaves of the coffee tree at the age of ten years and growing in a latosol of Piracicaba, State of São Paulo, Brasil (Table 1).

In this paper the authors describe the results obtained from the determination of molybdenum in sugar cane plant, grown in soils and climate prevailing in Piracicaba, State of São Paulo, Brazil. The molybdenum was determined in samples cut monthly from the 8th to 14th month, from an experiment consisting of 6 plots, 3 fertilized and 3 unfertilized. The fertilized treatment received 40 kg N (ammonium sulfate) 100 kg P2O3, (superphosphate) and 40 kg K2O (potassium chloride) per hectare, just before planting. Molybdenum was determined by thiocyanate-stannous chloride method, using carbon tetrachloride-butyl alcohol misture, for extrating the colored complex. The results obtained show a parallelism in the absorption of molybdenum by the plants of both treatments. The concentration of molybdenum in the stalks have a tendency to decrease, where as it kept more or less constant in leaves, with a exception in the 14° month when it rised probable because of a migration of molybdenum of the stalks to the leaves. The total amount molybdenum taken up was higher with the fertilized plot due its greater mass prodution.

O presente trabalho relata os dados obtidos na separação do estrôncio do cálcio, pelo uso de uma solução de NH4- EDTA, com pH entre os valores 4,8 e 5,3, passando através de uma coluna de resina trocadora de cátions. Assim, 200 ml de uma solução a 2,5% de NH4- EDTA com pH = 4,8 e contendo 0,36 mg de estrôncio e 199,2 mg de cálcio (o que dá uma relação de 1 de Sr para 553 de Ca) foram passados através de uma coluna de 25 a 28 ml de resina trocadora de cátions Amberlite IR - 120 (H+) prèviamente preparada. O estrôncio ficou retido na coluna e o cálcio continuou na solução que passou. Depois de passar solução de NH4- EDTA com pH 5,3 e solução de HCl de 0,25 a 0,75 N, o estrôncio foi eluido com solução 3N de HCl. Como empregou-se estrôncio radioativo Sr-89, esse ion foi determinado por radiometria, para se conhecer a eficiência da separação. O cálcio foi determinado pelo método permanganométrico em solução de NH4- EDTA após a eliminação do agente quelante. Os dados obtidos mostraram que houve uma separação muito eficiente, indicada pela porcentagem de recuperação do estrôncio qu efoi de 97,7, 97,0 e 98,6% ao passo que a recuperação do cálcio foi de 100,0, 99,9 e 99,7%.

A simple, rapid and efficient method of separation of strontion from calcium can be perfomed by using a solution of 2.5% NH4- EDTA, with pH adjusted to 4.80 to dissolve those cations. After, the solution is passed through a 25-28 ml column of the Amberlite 1R-120 (4+) cation exchange resin. Strontinum is quantitatively retained on the resin, while calcium passes through. After removal of ammonium ions with 0.25 to 0.75 normal solution of HC1, the strontium is eluted with 3 normal solution of HCl. The method was used to separate strontium and calcium from prepared strontinum-calcium mixture containing 0.36 mg of Sr with radioactive strontinum Sr-89 and 199.2 mg of Ca. The recovery of strontinum was 97.7, 97.0, and 98.6% in three replications and the recovery of calcium was 100.0, 99.9 and 99.7%. The strontinum was determined radiometrically with the "1000" Scaler, model SC-33, Tracerlab, Inc.

O presente trabalho relata os dados obtidos na determinaçao do zinco em plantas segundo uma nova técnica. Esta nova técnica consistiu em se aliar a separação do zinco de outros interferentes, através do emprego de uma coluna de resina trocadora de anions, ao método polarografico da dosagem do citado elemento. A amostra de planta (1, 000g) foi incinerada em copo de Pyrex a 450-5009C durante 90 minutos e o zinco foi extraido da cinza com solução de HC1 2N. A separação do zinco de outros elementos interferentes foi feita pela passagem da solução através da resina trocadora de anions, Amberlite, IRA-401. Após a eluiçao do zinco da coluna, a solução obtida foi levada ao polarografo registrador. (Sargent, modelo XXI) para a determinação, Trabalhando-se com um conjunto de 10 (dez) a 12 (doze) colunas de resina, pode-se executar 10 (dez) a 12 (doze) determinações num periodo de 6 (seis) horas.

This paper deals with the polarographic determination of zinc in plants after its separation with an anion exchange resin column. One gram of plant was ashed in a 20 ml beaker at 4505009C for 90-100 minutes. The solution of plant ash in 2N hydrochloric acid was passed through the column formed by a resin bed (Amerlite IRA-401) of 9 cm of length, which adsorbed zinc in the form of an anion an allowed to pass all the interfering ions. Twenty ml of 0,125 N sodium nitrate solution was used to elute the zinc and the effluent was dried in silica dish in vapour bath. Ten ml of 0, 35 N ammonium hydroxide with 0, 0125 % of gelatin, were added to the dish and the solution was stirred in order to dissolve the zinc. Three to five ml of solution were transferred to one special cell of the Sargent Visible Recording Polarograph Model XXI and the polarogram were obtained with the dropping mercury electrode and the stationary pool of mercury as the second electrode. Some of the obtained data are presented: PLANT Micrograms of zinc Micrograms %Recuperation added to the sample of zinc found (average) Coffee (leaves) 0,0 9,2 Coffee (leaves) 0,0 9,2 Coffee (leaves) 0,0 9,2 Coffee (leaves) 20,0 29,2 Coffee (leaves) 20,0 30,4 101,4 Coffee (leaves) 20,0 29,2 Sweet Clover (aerial part) 0,0 22,4 Sweet Clover (aerial part) 0,0 22,4 Sweet Clover (aerial part) 0,0 21,2 Sweet Clover (aerial part) 20,0 42,4 Sweet Clover (aerial part) 20,0 43,6 101,9 Sweet Clover (aerial part) 20,0 42,4 Sugar Cane (leaves) 0,0 12,0 Sugar Cane (leaves) 0,0 12,0 Sugar Cane (leaves) 0,0 10,8 Sugar Cane (leaves) 20,0 31,8 Sugar Cane (leaves) 20,0 31,8 100,6 Sugar Cane (leaves) 20,0 31,8 With the proposed method it is possible to analyse ten to twelve plant samples in six hours.

O presente trabalho relata os dados relativos a análise qualitativa e quantitativa do precipitado, que se forma quando se adiciona a uma solução contendo estrôncio, dicromato de potássio, em meio amoniacal e hidroalcoólico. Em lugar de se formar cromato de estrôncio simples, SrCrO4, forma-se um cromato que além do estrôncio, contém os ions amônio e potássio. Soluções padrões contendo desde 1, 8 até 50,5 mg de estrôncio, foram tratadas com solução de dicromato de potássio 2 normal, amoníaco e solução hidroalcoólica com 95% de álcool absoluto. O precipitado foi pesado e a equação de regressão que relaciona o peso do estrôncio colocado e o peso do precipitado obtido, e a seguinte: Y = 4,58 X + 0, 84, onde: X é o pêso em miligramas, do estrôncio colocado Y é o pêso em miligramas, do precipitado A composição provável do precipitado parece ser 6 SrCrO4 (NH4)2 CrO4. 6K2CrO4

This paper describes the data obtained concerning qualitative and quantitative analyses of the precipitate formed when to a solution containing strontium ion are added potassium dichromate, ammonium hydroxide and 95 per cent alcohol. Three replications of standard solution containing 1.8, 4..4, 8.8, 13.7, 27.5, 41.2, and 50.5 mg of strontium were treated with potassium dichromate and then, with constant stirring 95 per cent of alcohol and ammonium hydroxide. The precipitate was allowed to stend for two hours and afterward was centrifuged, washed with 95 per cent alcohol dried at 80ºC for 14-16 hours and weighed. Qualitative analysis of the precipitate showed potassium and ammonium ions, besides strontium and chromate. The relationships between the weight of strontium and the weight of the precipitate obtained is given by the regression line expressed by the equation: Y = 5.48 + 0,84, where X, is the weight of strontium in milligram Y, is the weight of the precipitate in milligram The value 4, 58 for the B parameter of the regression equation and the qualitative and quantitative analysis of the precipitate, suggested that its composition must be quite different from the simple strontium chromate SrCr0(4). The data allow to admit the following probable composition: 6 SrCrO4 . (NH4)2CrO4 . 6K2CrO4

O presente trabalho relata os dados obtidos, segundo uma modificação do método de Neubauer, comparados aos obtidos pelo método usual do citado autor. A modificação consistiu no uso de cristalizadores menores e no emprêgo de um número de plantas e de um pêso de terra muito menores. Assim, foram colocadas 25 sementes de arroz em 20 g de terra, intimamente misturadas com 40 g de areia de praia lavada, em cristalizadores de 80 mm de diâmetro, por 20 mm de altura. Decorridos 18 dias após a germinação, as plantas foram colhidas, incineradas e o potássio foi determinado por fotômetro de chama. Os resultados foram comparados com os dados obtidos através de um experimento feito com as mesmas amostras de terra e no mesmo tempo, conforme a técnica usual de Neubauer. Praticamente, os dois métodos se equivalem, conforme mostram os dados do quadro 1 em Resultados e Discussão. As principais vantagens do método modificado, em relação ao método usual de Neubauer, podem ser resumidas nas seguintes: redução do pêso da amostra de 100 para 20 g e redução do pêso da areia de praia lavada de 350 para 70 g; redução da área ocupada pelos cristalizadores para menos de um terço; redução do número de plantas para um quarto (de 100 para 25 plantas) e redução do trabalho exigido para a execução do método, desde o preparo dos cristalizadores, até o preparo das plantas, incineração e análise.

A MODIFICATION OF THE NEUBAUER'S METHOD This paper reports the data obtained, from a modification of the Neubauer method, as compared to the data obtained from the original one. The modification consistec of using smaller crystallizing dishes, and both a very small number of seedling and weight of soil. Thus, there were seeded 25 rice grains in 20 g of soil, very well mixed with 40 g of beach washed sand, in crystallizing dishes having 8C mm in diameter and 20 mm in height. Eighteen days after germination, the seedling were pulled out, their roots washed dried, ashed and its potassium determined by the flame photometer method. The results were compared with the data obtained from an experiment carried on with the same soil samples, at the same time, according to the usual Neubauer technique. Both methods are practically equivalent, as can be seen from the data on Table I in Results and Conclusions, in the Portuguese text. The main advantages of the modified method over the usual Neubauer method may be summarized as follows: reduction of both the soil sample weight from 100 to 20 g and the washed sand from 350 g to 70 g; the room taken by the crystallizing dishes is less than one third; the number of seedlings is reduced to one forth (from 100 to 25) and it takes less work for the handling of the experiment in all its steps.

Twelve samples of fluid milk delivered by "Laticínios Piracicaba Ltda." for public consumption, from March 25 do August 7, 1959, were analysed to determine its calcium and phosphorus content per 100 ml. A slight variation was observed. Calcium varied from 119 to 136 mg and phosphorus from 83 to 91 mg. These results are comparable to the ones obtained in other countries, showing that calcium and phosphorus content in cow milk is almost invariable.

For the determination of exchangeable hydrogen ion in soils, the authors of the presente work made the extraction with normal calcium acetate solution that may have an initial pH between 7 and 8 without altering the amount of hydrogen ion extracted. The extraction was made by shaking 5,0 grams of air dry soil with 100 ml of normal calcium acetate solution, the pH of wich was ascertained to 7,0, 7,5 and 8,0 with acetic acid, in 250 mil conical flasks for 30 minutes in a Wagner shaker (30-40 rpm). The contents of the flasks were then, filtered. A 50 ml aliquot of each of the leachate was titrated with a 0,020 N NaOH solution and the volumes consumed sodium hydroxide were ploted against pH. The titration curves thus obtained showed to be straight lines between pH 8 and 9 and parallel to the curve obtained by the titration of the blank. Two ways of locating the end point of the titration showed to be possible: the use of a pHmeter or titrimeter or the use of phenolphtalein as indicator. When using a pH meter or a titrimeter, the end point may rest in any point between pH 8 and 9, and the volume of sodium hydroxide consumed is found by comparison with a similar curve obtained by the titration of the blank. When using phenolphtalein the calcium acetate solution must have a pH below 8.

Com o objetivo de conhecer a quantidade de nitrogênio do ar fixado simbiòticamente pelas bactérias que vivem associadas às raízes da soja foi instalado o presente experimento, em vasos de Mitscherlich contendo terra-roxa-misturada, sendo os seguintes os tratamentos empregados: 1) testemunha; 2) NPK; 3) NPK + calcário; 4) NPK + inoculante; 5) NPK + calcário + inoculante; 6) PK + calcário + inoculante; 7) PK + calcário. O ensaio foi conduzido até a época do florescimento das plantas, quando então foram colhidas a parte aérea e a subterrânea, sêcas e analisadas em seu teor de nitrogênio. Os resultados obtidos permitem concluir que a soja não apresentou, neste experimento, grande capacidade fixadora de nitrogênio do ar atmosférico.

The experiment reported in this paper was carried out to determine the amount of nitrogen fixed from the air by nodule bacteria associated with soybean roots. The soybean plants were sown in Mitscherlich pots filled with the "terra-roxa-misturada" type of soil that had received the following treatments: 1) check; 2) NPK; 3) NPK 4- limestone; 4) NPK + inoculant; 5) NPK + limestone + + inoculant; 6) PK + limestone + inoculant; and 7) PK + limestone. When the plants started to blossom, both the aerial part, as well as the roots were collected separately, dried, and analysed for their nitrogen content. The soil was also analysed prior to planting and after the plants had been harvested. The results indicated that under the conditions of the experiment the symbiotic association - nodule bacteria plus soybean - did not show, a great capacity for fixing nitrogen from the air.

No presente trabalho são apresentados os resultados obtidos em dois experimentos de adubação de cana-planta, instalados na Usina Tamôio, em Araraquara, e na Fazenda Santa Escolástica, em Araras, realizados de 1955 a 1956. O objetivo foi o de estudar o efeito de diversas formas de fertilizantes fosfatados na cana-de-açúcar. Empregando um delineamento em blocos ao acaso com nove tratamentos e seis repetições estudaram-se, em presença de nitrogênio e potássio e na dose de 100 kg/ha de P2O5, os seguintes fertilizantes fosfatados: superfosfato simples, fertifós, farinha de ossos degelatinados, hiperfosfato, fosfato da Flórida, fosfato de Pernambuco e fosfato do Morro do Serrote. Os resultados obtidos mostraram que os efeitos produzidos pelos diferentes adubos fosfatados são equivalentes.

The influence of several phosphate fertilizers on the sugar cane yield was studied in two field experiments. One was carried out on the "terra-roxa" type of soil at the Usina Tamôio, Araraquara; and the other on "terra-roxa-misturada" at the Fazenda Santa Escolástica, Araras. The fertilizers were applied at the following rates per hectare: P2O5 100 kg; N, 60 kg; and K2O, 60 kg. The 9 treatments given below were compared in randomized blocks with 6 replications. The statistical analysis of data from the two experiments permitted tho following conclusions to be drawn: a) all phosphate sources induced a satisfactory response and increased the yield when compared with the controls; b) there was no significant difference in yield due to the source of phosphorus; c) the phosphates of higher solubility showed an early favorable influence on growth and number of sprouts per plant when compared with the lesser soluble ones, but this early beneficial effect was not followed by any significant yield increase.

Neste trabalho são apresentados os resultados preliminares obtidos em terra massapê-salmourão da Usina Itaiquara, município de Tapiratiba, em três ensaios com diferentes fertilizantes fosfatados. No ensaio instalado em 1950, em presença de nitrogênio e potássio foram estudados oito tipos de adubos fosfatados, na dose de 120 kg/ha de P2O5 verificando-se que, estatísticamente, deram os mesmos resultados: superfosfáto'simples, serranafosfato, farinha de ossos degelatinados, farinha de ossos autoclavados, hiper-fosfato, fosfato argeliano e fosfato do Morro do Serrote. A bauxita fosforosa mostrou-se inferior ao superfosfáto e às duas farinhas de ossos. Em outros dois experimentos, instalados em 1952, foram estudados cinco tipos de fertilizantes fosfatados, nos níveis de 0, 40, 80 e 120 kg/ha de P2O5. e os resultados mostraram que não houve diferença entre o superfosfato simples, farinha de ossos degelatinados, fosfato bicálcico (fertifós) e hiperfosfato; o fosfato do Morro do Serrote foi inferior a êsses fertilizantes.

The application of various types of phosphate fertilizers to sugar cane was compared in 3 experiments carried out in soil of the "massape-salmourao" type at the Usina Itaiquara, Tapiratiba. In a first trial, nitrogen and potassium were applied uniformly to all plots receiving fertilizers, and 8 different types of phosphates were compared at the rate of 120 kg of P2O5 per hectare. In two other tests a uniform rate of NK was applied, and four levels, 0, 40, 80 and 120 kg per hectare, of 5 phosphate fertilizers were compared. The results obtained in the three tests permitted the following conclusions: a) In a "massape-salmourao" soil with high acidity, a good increase in cane tonnage was obtained by the application of NK alone, when this treatment was compared with control plots receiving no fertilizer. The yield increase was considerably greater when phosphate in any of the forms was applied. There was no statistical difference in the cane yields obtained with the use of superphosphate, degelatinated and steamed bone meal, "serranafosfato", "hiperfosfato", Argelian phosphate, and a local rock phosphate (Morro do Serrote). Superphosphate and the two types of bone meal were statistically better than a type of phosphorated bauxite, but there was no difference between this and the remaining treatments. b) In "massapê-salmourão" soils of low acidity there was no statistical difference between the applications of phosphorus as superphosphate, degelatinated bone meal, "fertifós", and "hiperfosfato"; all these treatments were better than rock phosphate (Morro do Serrote).

Neste trabalho são apresentados os resultados obtidos em estudos preliminares sôbre a determinação da intensidade e evolução do fenômeno de amonificação e nitrificação em diversos fertilizantes nitrogenados, empregando-se terra roxa-misturada e os seguintes fertilizantes: sulfato de amônio, uréia, torta de mamona, farinha de sangue, farinha de chifres e cascos e calciocianamida. Os resultados obtidos permitem concluir que a calciocianamida foi o fertilizante que se amonificou mais intensamente, vindo a seguir a uréia, a torta de mamona, a farinha de sangue e, finalmente, a farinha de chifres e cascos. Já para o fenômeno de nitrificação, os resultados indicam a seguinte ordem decrescente: torta de mamona, uréia, farinha de chifres e cascos, farinha de sangue e sulfato de amônio. A calciocianamida, dosada no seu teor em nitrogênio nítrico, apresentou sempre traços, mostrando que foi praticamente nula a sua nitrificação no prazo de 40 dias de duração do ensaio.

In this paper results obtained with the phenomenon of ammonification and nitrification in several nitrogen fertilizers are presented. The objective was the determination of the intensity and evolution of these phenomena. For this purpose an experiment was set up including the following nitrogenous fertilizers: ammonium sulfate, urea, castor bean cake, blood meal, horn and hoof meal and calciumcyanamide. The experiment was conducted during 40 days; after each ten days period, samples of the different treatments were taken and ammoniacal and nitric nitrogen were determined. The results obtained show that the calciumcyanamide fertilizer ammonified more intensively, being followed by urea, castor bean cake, blood meal and finally horn and hoof meal. On the other hand concerning the phenomenon of nitrification, the results indicate that the castor bean cake nitrified the most, being followed in descrescent order by urea, horn and hoof meal, blood meal and ammonium sulfate. Results of calciumcyanamide analyses always presented traces of nitric nitrogen, showing that practically no nitrification ocurred during the 40 days of the experiment.

O trabalho teve por objetivo comparar a eficiência de calcários calcítico e dolomíticos na correção da acidez do solo e sua influência no crescimento da planta e na composição química em cálcio e magnésio, das fôlhas. O ensaio foi instalado com soja, em vasos de Mitscherlich e constou de oito tratamentos com três repetições. Todos os vasos receberam igualmente N, P2O5 e K2O nas formas de nitrato de amônio, fosfato de amônio e nitrato de potássio. Foram utilizados três calcários diferentes : um altamente cálcico, um dolomítico sedimentar e um dolomítico típico, em quantidades equivalentes quanto ao valor neutralizante total. O grau de finura dos materiais calcários foi dado por uma mistura, em partes iguais, das frações limitadas pelas peneiras Tyler de 65-150 e 150-270 malhas por polegada. Ao cabo de 2 meses e meio, as seguintes observações e determinações foram feitas : a) reação do solo (pH) e hidrogênio trocável; b) teor de cálcio e magnésio nas fôlhas; c) desenvolvimento da planta e pêso de material sêco. Os resultados obtidos permitem concluir que nas condições da experiência em estufa, com o tipo de solo terra roxa misturada, nível químico do solo empregado e com o grau de finura do material utilizado, o comportamento dos calcários calcítico e dolomíticos no solo foram virtualmente iguais no aumento do valor pH e no decréscimo de H+ trocável. A quantidade de calcário adicionada, calculada para elevar a saturação em bases do solo a 70%, elevou o pH do solo a um valor satisfatório em relação ao esperado. Quanto ao desenvolvimento da soja, os calcários acarretaram aumento de produção de hastes e fôlhas. Os calcários dolomíticos produziram maior pêso de material sêco.

A study was made of the effect of three types of finely powdered limestone (calcitic, typical dolomitic, and sedimentary dolomitic) on soil acidity, on the development of soybean plants growing in treated soil, and on the mineral content of their leaves. The experiment was carried out under greenhouse conditions in Mitscherlich pots filled with the "terra roxa misturada" type of soil. Eight treatments with three replications were compared. Equal amounts of N, p2o5, and K2O were added to all pots, except to one of the controls. Another control received the fertilizers but no limestone. Two levels of each of the three types of limestone were tested. The limestones were finely powdered, and a mixture of equal parts of the fractions obtained through the Tyler sieves 65-150 and 160-270 was used. The following data were taken 2¹/2 months after the experiment was started: a) soil reaction (pH) and exchangeable hydrogen; b) calcium and magnesium content of the leaves; c) growth of the plants and weight of dry matter. The results obtained indicated that under the conditions of the experiment the three types of limestone induced the same changes in pH and the same decrease of exchangeable hydrogen in the soil. Amounts of limestone sufficient to saturate about 70% of the exchange capacity increased the pH to a satisfactory level as was expected. The three types of limestone increased the growth of the plant and the amount of dry matter produced. The dolomitic limestone gave the greatest increases. For the same type of limestone the increase in dry matter was greater in plants that received the higher level of the treatment.

O presente trabalho foi realizado com a finalidade de estabelecer um sistema e técnica mais adequados de se coletar amostras de terra, para fins de estudo de fertilidade. Foram escolhidas duas áreas de solos diferentes. Uma delas com seis hectares, situada na Estação Experimental de Ribeirão Prêto, em solo tipo terra roxa legítima ; a outra com quatro hectares e localizada na Fazenda Santa Maria, em Pindorama, em solo do tipo arenito Bauru. A retirada das amostras de cada área foi feita com tubos especialmente construídos para esse fim e obedeceu ao seguinte critério: 1) 30 amostras simples, cobrindo tôda a área ; 2) 10 amostras compostas, formadas de cinco amostras simples, cobrindo tôda a área. 3) 5 amostras compostas, formadas de 20 amostras simples, cobrindo tôda a área. Nessas amostras foram determinados : pH, carbono total, potássio "trocável" e cálcio "trocável". Diante dos dados obtidos e levando-se em conta o trabalho exigido no laboratório, aconselha-se a retirada de três amostras compostas formadas de 20 simples cada uma, em glebas uniformes, de cinco hectares aproximadamente.

The following methods of collecting soil samples for fertility studies were compared : 1) thirty individual samples covering the whole area ; 2) ten composite samples, each consisting of five individual samples, covering the whole area ; 3) five composite samples, each consisting of 20 individual samples, covering the whole area. The three types of samples were collected in each of two plots : 1) a six-hectare plot in the Estação Experimental de Ribeirão Prêto, representing the "terra roxa" soil; 2) a four-hectare plot in the Santa Maria Farm, Pindorama, where the soil is of the "arenito de Bauru" type. The pH, total carbon, and exchangeable potassium and calcium were determined in the samples. Based on data obtained in the present investigation and considering the amount of work involved in the routine laboratory tests, it is suggested that three composite samples, each consisting of 20 individual samples, are quite satisfactory for fertility studies of uniform land areas of about six hectares.

Com a finalidade de conhecer a quantidade de nitrogênio fixado simbiòticamente por crotalária (Crotalaria juncea, L.) e mucuna anã (Stizolobium deeringianum, Bart.) e a influência de alguns fatôres sôbre o fenômeno, instalou-se uma experiência em vasos de Mitscherlich contendo solo tipo terra roxa misturada. Os tratamentos empregados foram os seguintes : 1) testemunha ; 2) NPK ; 3) NPK + calcário ; 4) NPK + inoculante ; 5) NPK + calcário + inoculante; 6) PK + calcário; 7) PK + calcário + inoculante. Dois meses após a germinação das sementes colheu-se o material para análise, dosando-se o N nas raízes e nas partes vegetativas das plantas. Nessa ocasião foram tiradas diversas fotografias, para documentação comparativa da nodulação das raízes nos diversos tratamentos.

A study was made of nitrogen fixation by bacteria in association with crotalaria (Crotalaria juncea L.) and velvet bean (Stizolobium deeringianum Bart). The experiment was performed according to the Mitscherlich pot technique. Three replications of each of the following treatment were made : 1) check ; 2) NPK ; 3) NPK + limestone ; 4) NPK + inoculation ; 5) NPK + limestone + inoculation ; 6) PK + inoculation ; 7) PK + limestone + inoculation. The amount of nitrogen, phosphorus, potassium, and limestone added to the pots that received these elements were as follows : 2.0 g of N in the form of NH4 NO3 ; 2.2 g of P2O5 as K2HPO4 ; 3.0 g of K2O as K2 HPO4 and KCl; 15 g of a dolomitic limestone in order to increase base saturation in the soil to 60 per cent. Inoculation of the seeds was made with a Rhizobium from the cowpea group. The plants were allowed to grow for two months and were then cut, dried at 60° C, and weighed. The roots were dug, washed carefully, and photographed to show the differences in nodule formation (figures 1 and 2). Nitrogen was determined separately in the stems with leaves and in the roots. This element was also determined in soil samples from treatments n.° 6 and n.° 7 prior to planting and after the plants had been removed from the pots. The data obtained indicated that nitrogen had not been absorbed from the soil. The amount of nitrogen fixed per pot by the nodule bacteria is given below : Treatment Nitrogen fixed by Crotalaria Velvet bean (g) (g) N.º 6 (PK + limestone) ------------------------------------------------------------- 0,52 1,18 N.° 7 (PK + limestone + inoculation) -------------------------------------------- 0,74 1,20