Soil Air Capacity Research Articles

Qualidade física do solo em pastagem adubada e sob pastejo contínuo

O objetivo deste trabalho foi avaliar a qualidade física do solo em pastagens submetidas ao pastejo contínuo. As pastagens foram formadas com capim-coastcross (Cynodon dactylon) consorciado ou não com a leguminosa amendoim forrageiro (Arachis pintoi). A pastagem consorciada recebeu os tratamentos de 0, 100 e 200 kg ha-1 de nitrogênio (N) por ano e a pastagem sem consórcio recebeu 200 kg ha-1 de N por ano, no total de quatro tratamentos. O experimento foi implantado em 2002, em Latossolo Vermelho distrófico, em Paranavaí, PR, em delineamento de blocos ao acaso, com duas repetições. A taxa de lotação animal foi controlada em função da oferta de forragem, entre 2002 e 2007. Em março e novembro de 2007 foram coletadas amostras indeformadas de solo, nas camadas 0-75 e 75-150 mm de profundidade, para determinação da densidade, porosidade e capacidade de armazenamento de ar e de água do solo. O pastejo em sistema de lotação contínua, com controle da taxa de lotação animal em função da produção de forragem, não comprometeu a qualidade física do solo. A capacidade de armazenamento de água do solo é um indicador sensível para se avaliarem os efeitos da intensificação da utilização da pastagem sobre a qualidade física do solo.

Changes in the main physical properties of ordinary chernozems under the impact of irrigation

The character of the quantitative changes in the main physical properties of ordinary chernozems under the impact of irrigation has been studied. It is shown that irrigation leads to a weak or moderate degradation of the aggregate state of the soils and a weak degradation of the soil bulk density, total porosity, and air capacity.

Optimal soil physical quality inferred through structural regression and parameter interactions

Soil physical quality (SPQ) is assessed by comparing values of “indicator” soil properties (e.g. bulk density, air capacity) to “ideal ranges” established in the literature. These ideal ranges may not be optimal for any particular soil or field site, however, as they are only “guidelines” based on broad soil types. The objective of this study was to determine if more relevant estimates of optimal indicator ranges can be obtained by using structural (Model II) regression to account for soil/site-specific indicator behaviour and interactions among the indicator parameters. The indicator parameters included relative water capacity (RWC), organic carbon content (OC), bulk density (BD), bulk soil air capacity (AC B), soil matrix air capacity (AC M), macroporosity (POR P), matrix porosity (POR M), field capacity (FC), plant-available water capacity (PAWC), and saturated hydraulic conductivity ( K S). The indicators were determined using intact soil cores collected from the top 10 cm of a uniform, cool, humid clay loam soil under maize–soybean cropping, continuous bluegrass sod, and virgin soil. The structural regression analysis was applied by regressing RWC, OC, AC B, AC M, POR P, POR M, FC, PAWC and K S against BD using the “least squares bisector” method. Structural regression predicted soil/site-specific optimal ranges of 3 ≤ OC ≤ 4 wt.%, 1.10 ≤ BD ≤ 1.23 Mg m − 3 , 0.16 ≤ AC B ≤ 0.22 m 3 m − 3 , 0.07 ≤ AC M ≤ 0.10 m 3 m − 3 , and 0.09 ≤ POR P ≤ 0.13 m 3 m − 3 , which are either narrower than the corresponding literature guidelines, or partially overlapping the guidelines. The regressions also provided information that is not currently available in the literature, including a possible optimal range for FC (0.30 ≤ FC ≤ 0.35 m 3 m − 3 ), and plausible “upper limits” to the optimal ranges for AC B, AC M and POR P (see above). Optimal ranges were not obtainable for POR M and PAWC because they were effectively constant among the cropping and sod treatments. A questionably high optimal range was obtained for K S (8 × 10 − 2 ≤ K S ≤ 7 × 10 − 1 cm s − 1 ), and this was attributed to the perturbing effects of large, highly water-conductive macropores. The overall SPQ at the field site was judged by structural regression to be “poor” for maize–soybean cropping, “good” for bluegrass sod, and “fair” for virgin soil. It was concluded that structural regression is useful for determining soil/site-specific optimal ranges for SPQ indicators.

Homogeneidade da qualidade física do solo nas entrelinhas de um pomar de laranjeira com sistemas de manejo da vegetação permanente

A qualidade física do solo é fundamental para a sustentabilidade da produção citrícola. O objetivo deste estudo foi avaliar a homogeneidade da qualidade física do solo nas entrelinhas de um pomar de laranjeira com sistemas de manejo da vegetação permanente. O estudo foi realizado em um experimento com sistemas de manejo de solo nas entrelinhas de um pomar de laranjeira 'Pêra' sobre limoeiro 'Cravo', implantado em 1993 em um Argissolo Vermelho distrófico latossólico, em Alto Paraná, região noroeste do Estado do Paraná. O delineamento experimental utilizado foi de blocos ao acaso com três repetições. Os tratamentos de sistemas de vegetação permanente das entrelinhas foram: gramínea "mato-grosso" ou "batatais" (Paspalum notatum), leguminosa amendoim forrageiro (Arachis pintoi) e o sistema de manejo tradicional com dessecação das plantas espontâneas com herbicida. Em maio de 2003, coletaram-se 216 amostras de solo indeformadas no meio da camada de 0-15 cm de profundidade e em duas posições de amostragem, no rodado e entrerrodado do trator. As amostras de solo foram usadas para determinar o teor de água em diferentes potenciais matriciais, a densidade do solo, a porosidade total e a resistência do solo à penetração. Também foram calculados a distribuição do tamanho de poros, a capacidade de aeração do solo e o índice S. A inclusão da capacidade de aeração do solo e do índice S associado à distribuição do tamanho de poros permitiu melhor entendimento das alterações físicas resultantes do manejo do solo com vegetações permanentes nas entrelinhas do pomar de laranjeira. O aumento do volume de poros drenados sob a vegetação leguminosa reduz o teor de água do solo, confirmado pela maior capacidade de aeração e pelo índice S no rodado e entrerrodado. A qualidade física do solo na entrelinha do pomar de laranjeira mantida com gramínea é mais homogênea do que daquele com vegetações espontânea ou leguminosa.

Compaction of forest soil by logging machinery favours occurrence of prokaryotes

Soil compaction caused by passage of logging machinery reduces the soil air capacity. Changed abiotic factors might induce a change in the soil microbial community and favour organisms capable of tolerating anoxic conditions. The goals of this study were to resolve differences between soil microbial communities obtained from wheel-tracks (i.e. compacted) and their adjacent undisturbed sites, and to evaluate differences in potential anaerobic microbial activities of these contrasting soils. Soil samples obtained from compacted soil had a greater bulk density and a higher pH than uncompacted soil. Analyses of phospholipid fatty acids demonstrated that the eukaryotic/prokaryotic ratio in compacted soils was lower than that of uncompacted soils, suggesting that fungi were not favoured by the in situ conditions produced by compaction. Indeed, most-probable-number (MPN) estimates of nitrous oxide-producing denitrifiers, acetate- and lactate-utilizing iron and sulfate reducers, and methanogens were higher in compacted than in uncompacted soils obtained from one site that had large differences in bulk density. Compacted soils from this site yielded higher iron-reducing, sulfate-reducing and methanogenic potentials than did uncompacted soils. MPN estimates of H2-utilizing acetogens in compacted and uncompacted soils were similar. These results indicate that compaction of forest soil alters the structure and function of the soil microbial community and favours occurrence of prokaryotes.

Zum vegetativen wachstum von weinreben in abhängigkeit von pedohydrologischen und klimatischen faktoren: Ergebnisse einer vergleichsstudie an zwölf testparzellen im Südbadischen weinbaugebiet

Summary On the relationship between the vegetative growth of vines and pedohydrological and climatic factors Results of a study comparing 12 test sites situated in the vine-growing area of Sudbaden (SW-Germany) During the growing periods of 1972 and 1973, investigations in twelve test sites were carried out, each having vines of the ‘Rulander’ variety and were situated in the viticultural areas of Breisgau, Kaiserstuhl-Tuniberg and Markgraflerland (Sudbaden). In order to obtain a broad variation in the soil moisture content as well as in climatic differentiation, the test sites were chosen on 1) loess, which had been consolidated and terraced to a large extent (Kaiserstuhl, Tuniberg, Vorbergzone), 2) limestone and marl mixed with loess (Markgraflerland), 3) volcanic weathering material (Kaiserstuhl) and 4) a mixture of sand and gravel from the lower terrace (Oberrheinebene). Each experimental site had 30 genetically homogenous vines of the ‘Rulander’ variety (Pinotgris). During the growing periods (hydrological summer half-years 1972 and 1973), topoclimatic and pedohydrological factors, (atmospheric and soil temperature, evaporation of a ceramic disk according to CZERATZKI, total soil water and the actual available soil moisture in the profile of the main root zone) were measured either continuously, or at weekly and fortnightly intervals. The following vegetative factors in vine development were ascertained: weight of pruning wood and topping foliage (from which the vegetative production is determined) as well as the length of three internodes. Grain size and pore space distribution were plotted for characteristic sites. In order to ascertain the soil water actually available to the plants, the total soil moisture content, measured by means of a neutron probe, was reduced by subtracting the amount of bound water, which had been diverted, according to the methods developed by HARTGE (1969) and RENGER (1972) . The air capacity of soil was derived from the pore space distribution. By means of statistical evaluation, multiple linear regression and correlation calculations are discussed, taking into consideration the most significant dependent variables for ‘vegetative growth’ (weight of pruning wood and topping foliage, length of the 3 internodes of segment no. 6, and the vegetative production) in biological and hydrological relation to the abovementioned climatic and pedohydrological factors. The following relations were detected: 1) Evaporation of the ceramic disk according to CZERATZKI has, generally, the most influence; therefore, with increased evaporation, the weight of pruning wood and topping foliage and consequently vegetative growth is reduced, and the length of the three internodes of segment no. 6 is shortened. 2) In both experimental years, the effectiveness of soil water proved to be the second most important influence. Increased soil water content available to plants produced an increased vegetative growth of the vines. In the relatively dry year of 1972, a greater significance in the effectiveness of soil water was noticed. With the increased soil moisture in th year 1973, the soil water was of less significance. Therefore, the effect of the air capacity of the soil on vine is indicated. Attention is drawn to further coherence between vegetative growth strength and yield development and consequently the wine quality.

Studies on the Growth of Tobacco Roots : II. Effect of the bulk density and moisture content of soil on the thickening growth and branching of tobacco roots

In oder to determine the optimum value of soil air capacity on the plant root development, the auther studied the effects of different bulk densities and moisture contents in the soils upon the thickening growth and branching of tobacco tap root. 1. The root thickening growth and branching in artificially compacted soil: The soils used were taken from Hatano, Utsnomiya, Okayama and Shizunami, and seedings of the variety Bright Yellow were grown on the pots with soils of various moisture contents ranging from 40 to 100%. The auther obtained the air capacity for the optimum thickening growth of tap root as follows: Hatano soil, 20%; Utsunomiya and Okayama soil, 10%; Shizunami soil, 10∼15% (fig. 3) and for the branching of tap root: Hatano soil, 20%; Utsunomiya soil, 15%; Okayama soil, 1∼3%; Shizunami soil, 12∼14% (fig. 5). From these facts, the soil air capacity required for the thickening growth of tap roots was supposed to be different from that equired for the branching of the roots. 2. The root growth and branching in the field: It could not be found that air capacity in the soil was related to the thickening growth of the secondary roots (fig. 7). High level of the soil air content seemed to inhibit the thickening growth of roots. The root penetration was not inhibited in the region of tis experiment by high bulk density of the soil, but number of branching per unit root length was accelerated obviously.

Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : III. Effects of the capacity and composition of soil air on the growth and yield of sweet potato plants.

The authors clarified the relationship between the type of soil and various soil-managing methods (control of soil bulk density, moisture content, height of ridges and amount of fertilizers), on one hand, and the soil air capacity and the soil air composition, on the other, and studied the effects these factors would have on the growth and yield of the sweet potato plant. 1) The soil air capacity was found to decrease when the soil bulk density became higher or when the soil moisture content became larger. Also, the capacity in question was larger where the height of ridges was larger, than where the height in question was smaller. In terms of the type of soil, the capacity was smaller in the alluvial soil and larger in the volcanic ash soil. As for the change in the soil air capacity after tilling, the capacity decreased considerably in the alluvial soil with the lapse of time, while it decreased very slowly in the sandy soil. The air capacity of the volcanic ash soil was affected also by the soil-managing methods to a greater extent than that of the sandy soil. 2) In the brown-colored volcanic ash soil, the composition of air contained in it is closely related with its air capacity. The O2 concentration in the air in question was lowered when the soil air capacity became smaller, and the CO2 concentration in it increased under the same condition. But the effect was different depending on the type of soil a significant correlationship was observed between the soil air capacity and the CO2 concentration in the soil air in the case of the alluvia soil and the volcanic ash soil, but no such correlationship was noticed in the case of the sandy soil and the aggregated alluvial soil. 3) With regard to the relationship between the soil air capacity and the composition of soil air, on one hand, and the growth and yield of the sweet potato plant, on the other, the growth of the upper parts of the plants was male active when the CO2 concentration in the soil air was increased, whereas the growth of the tuberous roots was checked under the same condition, and as a result, the weight of the tuberous roots was reduced. All this goes to show that the soil air capacity needed to assure the growth of the upper parts of the plant is different from that required for the growth of the tuberous roots, and that therefore the different soil air capacities have their respective influences on the distribution of the substances produced through photosynthesis among the upper and underground parts of the plant.

Studies on the Effects of Soil Physical Conditions on the Growth and Yield of Crop Plants : II. Effects of the bulk density and moisture content of soil on the growth and yield of crop plants.

Using upland rice, soybean, sweet potato, soiling corn and cucumber as specimens, the authors studied the effects of the soils of different bulk densities and moisture contents (in this experiment, brown-colored volcanic ash soil was used) would have on the growth and yield of crop plants. The result was that the effects of the varying soil physical conditions due to the difference in its bulk density and moisture content were different depending on the kind of the crop plants used. But in all the kinds, conditions were largely influenced by the magnitude of the soil air capacity. In fact, the yield was lowered when the capacity in question was extremely small (or when the soil bulk density or moisture content was relatively high). In this case, the rate of decrease in the yield differed according to the kind of crop plants-the rate was high in the case of sweet potato plants (weight of tuberous roots), cucumber plants (number of fruits) and soybean plants (weight of grains), and was relatively low in the case of upland rice (weight of grains) and soiling corn (weight of parts protruding above the ground). In the authors' experiment, the yield of crop plants increased with the rise of the soil air capacity. When this capacity rose beyond a certain level, however, the moisture content of the soil decreased correspondingly, and as a result, the yield was lowered. This phenomenon was especially evident in the case of upland rice, and was least noticeable in soiling corn. Thus, the soil air capacity favorably affecting the yield of crop plants differed according to their kinds. The influence of the soil air capacity at various levels on the total weight of crop plants was, generally speaking, similar to such influence on their yield. In the case of sweet potato plants, however, the soil air capacity required for the growth of their upper parts was different from that required for the growth of their tuberous roots. That is to say, the soil air capacity, when decreased, had less unfavorable effects on the growth of the upper parts than on the growth of the tuberous roots. This goes to show that the effects of diffects of different soil air capacities differ from one part of the crop plant to another.

Studies on Ripening of Wheat and Barley in the Warmer Districts in Japan : 3. Relationship between ripening of wheat and barley and soil moisture content.

In order to clear the effect of excess soil moisture in ripening stage on grain quality of wheat and barley, pot-experiments were carried out from 1957 to 1960. The results were summarized as follows: 1000-grain-weight of kernel raised from the soil with air porosity below about 20 volume-percent of soil was significantly inferior to one from the control plot with larger air porosity. The lowering in production in the plot holding higher soil moisture was due to smaller air capacity, higher acidity and lower redox-potential of soil. In consequence, the plant grew poorly and declined in respiration and water absorption activities. The excess soil moisture in the first half of ripening stage was mose injurious than that in the second half on plant growing. High temperature encouraged excess soil moisture injury to plant ripening. The conclusion above-mentioned was supported by surveying those points in some practical wheat fields around Chikugo Area.