Soil Phosphorus Status Research Articles

Measurements of Phosphorus Availability In Acid Soils of Pennsylvania

The objective of this investigation was to compare extracting procedures which might be superior to the Morgan method for predicting the phosphorus status of soils in Pennsylvania. The first experiment involved the Ap horizons of 161 soil types. Of these, 44 soils were selected for additional experiments. Some of the soils tested either very high or very low in P by all methods, some tested high by one or more methods but not by other methods, and some fixed either high or low percentages of the added P against extraction by one or more of the methods. With respect to the amounts of P removed from soils, the extractants ranked in the order Purdue > Bray no. 1 > Morgan > Experimental > CaCl2. The respective extractants removed about 52, 38, 8, 4, and 1% of the P which was added and allowed to react with the soils. In general, the test values obtained by one method were not very closely related to values obtained by other methods for these soils. The Bray no. 1 method was most accurate for predicting plant uptake of P while the Purdue method proposed by Al-Abbas and Barber was least accurate.

Soil properties in relation to the sulphur and phosphorus status of some basaltic soils

Twenty-three basaltic soils from elevated areas in northern New South Wales were examined for sulphur and phosphorus status by growing Phalaris tuberosa L. in pots in a glasshouse. Sulphur deficiency was more common and more severe than was phosphorus deficiency. To determine whether there may be some topographic control of sulphur or phosphorus status, soil colour was examined, as in general the reddest soils were found in the highest positions in the landscape. The soils were first considered as one group and then as subgroups of sedentary, colluvial, and alluvial soils. Using redness to rank the soils, there was no overall relationship to sulphur or phosphorus status. However, colour of the sedentary soils was significantly correlated with sulphur status (r = 0.92***), the reddest soils being the most deficient. The sulphur status of the brown colluvial and greyish brown alluvial soils showed no relationship to colour; they were uniformly severely deficient. Phosphorus deficiency was not associated with soil colour. Neither soil pH nor redox potential was related to the sulphur and phosphorus status of the soils. There was only a weak correlation (r = 0.60**) between the water-soluble sulphur content of all soils, but a stronger correlation (r = 0.81**) when only the sedentary soils were considered. Several soil phosphorus fractions could be satisfactorily used to distinguish between phosphorus-deficient and phosphorus-sufficient soils.

Diagnose foliar em batatinha : estudo da amostragem

O presente trabalho foi idealizado com o objetivo de estudar alguns problemas, relacionados com amostras de folhas para fins de diagnose foliar em batatinha (Solanum tuberosum, L) em condições de campo. Algumas inferências desses estudos, seguem abaixo. O limbo da quarta fôlha traduziu melhor a situação do nitrogênio no solo aos 40 dias e aos 60 dias após o plantio. Tanto o limbo como pecíolo da quarta fôlha apresentaram bons resultados para análise do estado de fósforo no solo e os dados sugerem que o diagnóstico dêsse elemento na batatinha, através, da análise química das fôlhas, não deve ser feito muito além dos 40 dias após o plantio. Os valôres fornecidos para potássio e cálcio, embora discutíveis sob diversos aspectos, não foram suficientes para inferir a respeito de qual ou quais das partes da fôlha e qual dos pecíolos estudados se destinam melhor para amostra.

The nature of available phosphorus in some acid pasture soils and a comparison of estimating procedures

Several methods of evaluating the phosphorus status of soils for the growth of pasture plants were compared. NaHCO3 and NH4F in HCl were the most suitable extractants used. On these soils, differing widely in origin and fertilizer history, phosphorus values of 30 p.p.m, as determined by three of the methods distinguished responsive from unresponsive soils. For the other, the bicarbonate method of Olsen et al. (1954), the corresponding value was 15 p.p.m. The evidence suggests that in the soils examined, all inorganic forms of soil phosphorus, as determined by the method of Chang and Jackson (1957), contributed in some degree to the pasture plants needs. The principal source of available phosphorus, however, was the aluminium phosphates. On the other hand, the evidence suggests that the principal loss in the availability of residual phosphorus to the plant may be through its conversion to organic forms. Iron phosphates appeared to be the least available of the inorganic forms. The common ability of the four successful methods to efficiently extract phosphorus from the aluminium source appears to be the prime reason for their measuring the soil phosphorus status for plants equally well. The physical nature of aluminium phosphate, however, has a marked effect on its ability to supply the plant's phosphorus needs. A crystalline form was less available than an amorphous one. The greater availability of the amorphous forms, of both iron and aluminium phosphates, appeared to depend more upon their solubility than on their positional availability due to the greater specific surface presented. Fertilizer application enriches the aluminium phosphate content of the soils, but, in these experiments, the quantities found were related significantly to the total applications made in the previous three years only.

Progress of Agricultural Education in Mysore

The Hebbal School trained students for a post-secondary diploma course in Agriculture. The school earned a great reputation and attracted students from other States in India and outside from Ceylon, Burma, Malaya and other countries. It was during this period that agriculture was introduced as an optional subject for study in selected middle and high schools in various parts of the State. The staff resources in the Research Divisions particularly in earlier periods were very limited. As a result of devoted research work on the part of these few workers, many useful information of practical value to farmers have come out. In the Division of Entomology, considerable intensive work on the use of chemical pesticides and insecticides was done in the past two decades. In consequence, Folidol, BHC, DDT and other chemicals in the protection of crops from pests and insects have gained wide acceptance and popularity. In the Division of Botany many new varieties of sugarcane, paddy, groundnut, ragi and other crops have been evolved. Similarly, the Division of Agricultural Chemistry after sustained experimental work has recommended economic and optimum manurial schedule for the several crops in the different soil and climatic regions of the State. The demand for fertilizers is growing by leaps and bounds. It may be mentioned in this connection, that research conducted at Hebbal on the direct use of anhydrous ammonia as a nitrogenous fertilizer for crops is the first of its kind in the region East of Suez and South East Asia. The work on the influence of lime and phosphate on pod filling of groundnut and the build up of soil phosphorus status as a means of improvement of red soils belong to the category of fundamental research.

THE EFFECT OF VARIOUS ORGANIC AMENDMENTS ON CERTAIN CHEMICAL PROPERTIES OF SOIL, ON PLANT NUTRIENT LEVELS IN STRAWBERRY FOLIAGE AND ON FRUIT YIELDS

In a field experiment applications of manure decreased soil acidity but increased total nitrogen, organic matter and adsorbed plus easily acid–soluble phosphorus. Where either peat moss or sawdust was applied there was an increase in soil acidity, total nitrogen and organic matter. The effects of other treatments, e.g., hay and hay compost, were less marked.The phosphorus level in strawberry leaf samples from manured plots reflected the improved phosphorus status of the soil but none of the treatments resulted in significant differences in levels of nitrogen, potassium or calcium in the leaves.All treatments gave highly significant increases in yield. However, the yield with either hay compost or hay was significantly higher than with manure.

Assessment of the available phosphorus status of the soil during crop growth and factors influencing it

The influence of superphosphate and farm yard manuro on equal phosphorus basis and their combinations, on the available phosphorus status of soil was studied using two strains of ragi Co. 1 and Co. 7 and also in fallow plots throughout the growth period. Plots where Co.7 ragi was grown had higher amounts of available phosphorus. Plots receiving combinations of supor and farm yard manure had always higher amounts of available P than plots receiving them alone. Combinations com- prising low amounts of farm yard manure and higher amounts of superphosphate proved to be best. Superphosphate was better than farm yard manure when applied individually on equal P basis.

Field trials on the store dressing with rock phosphate

The possibility of improving the soil phosphorus status by a store dressing with rock phosphate has been studied in two field trials of five years standing. Hyperphosphate Reno was applied to the nurse crop of a red clover-timothy ley in amounts of 0, 1000 kg/ha, or 2000 kg/ha, respectively. The split-plot technique was used to study the response of the ley to an additional annual application of 200 kg/ha of superphosphate. The soil analyses distinctly proved that, in spite of a careful working in of the hyperphosphate with a spade harrow, the fertilizer had not penetrated deeper than to the layer from 1 to 3 inches, with a large part of it remaining in the top inch. The treatment with hyperphosphate had mostly increased the fraction of the calcium-bound phosphorus, and, to a very low degree, the aluminium-bound phosphorus. The effect of superphosphate could be detected only in the fractions of aluminium- and iron-bound phosphorus of the surface inch. Although the store dressing did not produce marked responses in the yields of either trial, the statistically significant negative interaction between the effect of it and of superphosphate may be taken to indicate that hyperphosphate was able to improve the phosphorus status of these soils to some degree. The analyses of the hay samples from one of the trials in the fifth experimental year showed that the store dressing, particularly with the higher amount of hyperphosphate was able to increase the phosphorus content of hay to a satisfactory level which was equal to that produced by the annual superphosphate dressing only. Their combined effect resulted in the production of hay dry matter containing more than 0.24 % of P. In one of the experiments the residual effect of the treatments on rye was studied. The response to superphosphate was highly significant, probably owing to the high demands of phosphorus by rye, connected with the overwintering conditions, and also to the fact that ploughing in of the ley had brought superphosphate phosphorus within the reach of the plant roots.

Studies of Phosphorus Availability in Organic Soils

AbstractExperiments were conducted on the phosphorus status of organic soils by correlating the phosphorus solubility in various extractants with percentage yields of tomato, peppermint, and onion. Seven different extractants, including water, were compared using four ratios of soil volume to extractant volume. Distilled water extracts gave the most accurate estimates of plant‐available phosphorus in a ratio of soil volume to extracting solution of 1:20 for the organic soils and 1:10 for the mineral soil.The threshold value at which yields were not increased with additional applications of phosphorus under greenhouse conditions was established at 10 and 16 pounds per acre of water‐soluble phosphorus when the soil and the water was shaken for 2 minutes and 30 minutes, respectively.

THE PHOSPHATE STATUS OF IRISH SOILS WITH PARTICULAR REFERENCE TO FARMING SYSTEMS

SummaryThe phosphorus status of selected permanent pasture and tillage soils has been examined by a fractionation technique. This has shown a distinct difference between the soils especially with regard to the organic‐phosphorus fraction. Some of the reasons for these differences are discussed.The readily available phosphorus level of a highly productive, permanent pasture soil which has received no phosphatic fertilizer for years was found to be good, indicating a satisfactory mineralization of organic phosphorus which was the only form in which this nutrient was added. Irrespective of whether phosphorus was added in the organic or inorganic form there was an appreciable accumulation in the surface 3 in. of permanent pasture, indicating stabilization of applied phosphorus in that zone. Adsorbed phosphorus constituted a relatively small proportion of the inorganic phosphorus, the latter faction varying but slightly in the different soils.A comparison between Morgan's solution (sodium acetate‐acetic acid) and other extractants showed that this solution provides a good index of phosphorus availability, when the P value of the extract is regarded as an intensity value.When phosphorus fractionation studies were carried out on four soils in hydrologic sequence and occurring in close proximity in an area unmanured for about a century, distinct differences in phosphorus categories were found. These differences were especially striking between the impeded and free‐draining members. They were further explored through the medium of fractionation studies on different textural fractions. The main difference was found in the organic‐phosphorus level and was associated with the fine‐clay fraction.The general significance of the results in relation to farming systems, the phosphorus cycle and methods designed to determine the phosphorus status of soils, is discussed.

A study of the available phosphorus status of soils by phosphorus-deficient tomato seedlings

Several important New York soils were evaluated for their phosphorus fertility status in the greenhouse by growing tomato plants and determining the relationship between the anthocyanin content of the plants and their response to added phosphorus. In general, there was an inverse relationship between the anthocyanin content of the leaves and increases in dry weight production when phosphorus only was the limiting factor.

Influence of Soluble Salts on the Solubility of and Plant Response to Dicalcium Phosphate

A considerable part of the phosphorus in most mixed fertilizers is carried as dicalcium phosphate produced as a consequence of ammonia neutralization of the mixture. Agronomic experience with such mixtures suggests that the phosphate produced in situ has a higher nutritive value than separate preparations of dicalcium phosphate. Any increased nutritive value of the dicalcium phosphate must, it would seem, stem mainly from enhancement of phosphorus solubility in the presence of soluble salts. Accordingly, the solubility of a laboratory preparation of dicalcium phosphate was measured in water and several salt solutions. Greenhouse techniques were designed to minimize responses to nutrient constitutents of the salts, change in available soil phosphorus status and physiological effects due to the salts, so that differences in plant response to binary mixtures of dicalcium phosphate and several salts were indicative of differences in solubility of dicalcium phosphate. Alfalfa was used as the test crop on Nunn, Carrington, and Chester soils. In general, salts such as ammonium sulfate, which in laboratory tests markedly increase the solubility of dicalcium phosphate with increasing ionic strength, also gave the greatest crop responses in the greenhouse. Those salts such as the ammonium nitrate type, which increase the solubility only moderately and level off at ionic strengths between 2 and 4, only occasionally gave increased crop response, while salts such as the calcium nitrate type, which decrease the solubility sharply with increasing ionic strengths, usually gave a negative crop response.

Loss of Phosphorus by Erosion

AbstractA study was made of the phosphorus status of soils which had received phosphate applications over a period of years to determine the loss of phosphorus by erosion. Phosphorus that could not be accounted for by analysis of the surface 16 inches of soil and by crop removal was assumed to be loss by erosion.Where corn and cotton was used as the rotation, an average of 63% of the phosphorus applied during a 16‐year period to a Hartsells fine sandy loam soil had been lost by erosion as compared to 40% for a corn, cotton, and winter legume rotation. The results show that most of the accumulated phosphorus could be extracted by a HCl‐NH4F solution. Three plots in the corn, cotton, and winter legume rotation contained 7 to 8% of < 2 µ material in the surface 0 to 8 inches originally, but after 16 years of cropping the < 2 µ material had been reduced to 5 to 6%. The clay fraction contained 25 to 30% of the total phosphorus. These results indicate that only a small part of the phosphorus was lost along with the clay fraction. A study of 22 fields in Baldwin County that had been in potatoes from 5 to 30 years shows that the surface soil accumulated an average of 103 pounds P2O5 per acre per year in potatoes, although an estimated 200 pounds of P2O5 was added each year potatoes were grown. An inventory of the phosphorus status of soils in cement bins after 12 years of phosphate applications shows that 80% or more of the applied phosphorus could be accounted for on the basis of soil analysis and crop removal. The plots were enclosed by cement walls which prevented run‐off except during very heavy rains.