Soil Physical Conditions Research Articles

Least limiting water range of the soil seedbed for long-term tillage and cropping systems in the central Great Plains, USA

Integration of dynamic soil physical properties using the least limiting water range (LLWR) approach may allow a better understanding of soil–crop relationships in tillage and cropping systems, particularly in regions with limited precipitation and low soil organic matter content. We determined the LLWR for long-term tillage and cropping system experiments on an Argiustoll in the central U.S. Great Plains. The tillage (46years) experiment consisted of wheat (Triticum aestivum L.)–sorghum [Sorghum bicolor (L.) Moench]–fallow (WSF) rotation under conventional tillage (CT), reduced tillage (RT) and no-tillage (NT), while the cropping system (35years) experiment consisted of wheat–fallow (WF), WSF and continuous wheat (WW) rotations managed under RT and NT. Soil water retention curves, penetration resistance curves and bulk density were determined for the 0 to 5cm and 5 to 10cm depths to compute the LLWR. Mean LLWR did not differ among tillage systems for the 0 to 5cm depth, but it was higher in RT and CT than in NT for the 5 to 10cm depth. Mean LLWR was higher for WW than for WSF and WF in RT at both depths, but it did not differ in NT. Across cropping systems, LLWR in RT was greater than in NT by 1.2 times for the 0 to 5cm and by 4.7 times for the 5 to 10cm depth. Analysis of the upper and lower limits of the LLWR suggested that aeration and penetration resistance were plant-growth limiting factors in both experiments. Both tillage and cropping systems were associated with a narrow LLWR, which may reflect the limited water availability in this semiarid region. Overall, the LLWR was a useful indicator of the soil physical condition for plant growth under these long-term tillage and cropping systems and indicated that RT may produce the best soil seedbed in the central Great Plains.

Effect of Tillage and Organic Mulches on Growth, Yield and Quality of Autumn Planted Maize (Zea Mays L.) and Soil Physical Properties

Abstract The research work was conducted to see the effect of organic mulches and tillage practices on growth, yield and quality of autumn planted maize and soil physical properties. Four types of tillage practices i.e. conventional tillage, zero tillage, bar harrow tillage, subsoiler tillage and two types of mulching material i.e. wheat straw mulch and saw dust mulch was used. The mulching material was partially incorporated in the field after germination of crop. The experiment was carried out in randomized complete block design (RCBD) with three replications. Control treatment was kept for comparison. All other practices were kept uniform throughout the crop period. Data about growth and yield components were collected and analyzed statistically by fisher analysis of variance and treatment significance was measured by significant difference test at 5v% level. The results showed that zero tillage + wheat straw mulch gave maximum 1000-grain weight (341.67 g) and grain yield (6.33 t ha-1) and it was followed by conventional tillage + saw dust mulch (4.92 t ha-1). Higher protein content was recorded in Subsoiler tillage (10.26 %). Conducive soil physical conditions were observed in the zero tillage practices over the other tillage practices. On the basis of these results it could be proposed that the tillage and mulching is a very important practice to increase the yield of crop. Among different practices, zero tillage with wheat straw mulching gave maximum yield and net benefits.

Effects of organic fertilizers on yam productivity and some soil properties of a nutrient-depleted tropical Alfisol

Field experiments were conducted at Owo, southwest Nigeria to select organic fertilizer treatments most suitable for sustaining high soil fertility and yam productivity on a nutrient-depleted tropical Alfisol. Eight organic fertilizer treatments were applied at 20 t ha−1 with a reference treatment inorganic fertilizer (NPK 15–15–15) at 400 kg ha−1 and natural soil fertility (control), laid out in a randomized complete block design with three replications. Results showed that organic fertilizers significantly increased (p = 0.05) tuber weight and growth of yam, soil and leaf N, P, K, Ca and Mg, soil pH and organic C concentrations compared with the NSF (control). The oil palm bunch ash + poultry manure treatment increased tuber weight, vine length, number of leaves and leaf area of yam by 66, 25, 21 and 52%, respectively, compared with inorganic fertilizer (NPK) and 37, 22, 19 and 44%, respectively, compared with poultry manure alone. Sole or mixed forms of organic fertilizers showed significant improvement in soil physical conditions compared with IF (NPK) and NSF (control). Synergistic use of oil palm bunch ash + poultry manure at 10 t ha−1 each was most effective for sustainable management of soils and for improving agronomic productivity of yam.

Influence of soil bulk density and matric potential on microbial dynamics, inorganic N transformations, N2O and N2 fluxes following urea deposition

Transformation of ruminant urine-nitrogen (N) can contribute to negative environmental outcomes such as nitrate leaching which leads to eutrophication of waterways and production of nitrous oxide (N2O), a greenhouse gas. Although abiotic factors influencing urine-N processing have been well studied, detailed studies of the soil microbial community dynamics following urine application are required to improve mitigation strategies for reducing harmful N fluxes from urine deposition. A factorial laboratory experiment using packed silt-loam soil cores with two levels each of urea (±), soil matric potential (ψ −6.0 or −0.2 kPa) and soil bulk density (ρb 1.1 or 1.5 g cm−3) was performed to study the interaction of urea and soil physical conditions on both soil inorganic N transformations and the abundance of ammonia-oxidizers and denitrifiers. Soil ψ and ρb treatments had an immediate impact on soil pH, dissolved organic carbon, inorganic N pools and emissions of N2O and N2 following urea deposition, and microorganisms carrying the nosZ gene were present in lower numbers in the most aerobic soil (−6.0 kPa and 1.1 g cm−3) from day 7. In all treatments, both bacterial amoA and denitrifier nirS, nirK and nosZ gene copy numbers increased within 1 day following urea application. Dynamics in the NH4+ concentrations were significantly correlated with cumulative changes in the abundance of the ammonia-oxidizers, but no relation was found between cumulative changes in the denitrifier nirS, nirK and nosZ gene copy numbers and the dynamics in soil inorganic N, N2O or N2 emissions. Throughout most of the study period the specific soil conditions, induced by the ψ and ρb treatments, determined nitrifier and denitrifier activity rather than the size of the microbial communities involved. However, by day 35 soil ψ and ρb treatments exerted large treatment effects on bacterial amoA, nirS and nirK gene copy numbers. Thus, although nitrate concentrations and N2O emissions following urea deposition were determined by the soil ψ and ρb conditions in the short-term, our results indicate that changes in the population sizes of denitrifiers and AOB in ruminant urine patches may influence environmental N fluxes in the long-term.

Microbial community responses to anthropogenically induced environmental change: towards a systems approach

The soil environment is essential to many ecosystem services which are primarily mediated by microbial communities. Soil physical and chemical conditions are altered on local and global scales by anthropogenic activity and which threatens the provision of many soil services. Despite the importance of soil biota for ecosystem function, we have limited ability to predict and manage soil microbial community responses to change. To better understand causal relationships between microbial community structure and ecological function, we argue for a systems approach to prediction and management of microbial response to environmental change. This necessitates moving beyond concepts of resilience, resistance and redundancy that assume single optimum stable states, to ones that better reflect the dynamic and interactive nature of microbial systems. We consider the response of three soil groups (ammonia oxidisers, denitrifiers, symbionts) to anthropogenic perturbation to motivate our discussion. We also present a network re-analysis of a saltmarsh microbial community which illustrates how such approaches can reveal ecologically important connections between functional groups. More generally, we suggest the need for integrative studies which consider how environmental variables moderate interactions between functional groups, how this moderation affects biogeochemical processes and how these feedbacks ultimately drive ecosystem services provided by soil biota.

A Comparison of Two Models to Evaluate Soil Physical Property Effects on Corn Root Growth

Two models for evaluating soil physical condition effects on root growth were compared. The first model, called the Jones model, is a submodel for root growth limitations used by several complex soil–plant–atmosphere models. The second model uses soil physical limitations as identified by the least limiting water range (LLWR). Root surface area density (Rsa) and bulk density (ρb) were determined at the V6, V12, and R1 growth stages of corn in 2004. Water contents (θ) throughout the growing season were determined twice per week with a neutron probe. The cumulative predicted relative root growth suitability (PRGS) was determined using soil physical limitations to root growth defined by each model. Significant plot‐to‐plot variability was observed in ρb and θ. The LLWR resulted in a wider range of PRGS for all sampling times and soil depths. Regressions using the LLWR criteria for soil physical limitations resulted in significant correlations between Rsa with PRGS at the expanding zone of root exploration, indicating more root surface area with better soil conditions. Regressions using the Jones criteria for soil physical limitations resulted in either a nonsignificant correlation between Rsa with PRGS or a linear, negative correlation, indicating less root surface area with better soil conditions. Using limitations of soil physical properties as identified by the LLWR in larger, more comprehensive plant and root growth models may provide a better response of these models to variable soil conditions.

Towards sustainable highland banana production in Uganda: Opportunities and challenges

East Africa highland bananas ( Musa sp., AAA- EA HB) are an important starchy food and cash crop in Uganda and the Great Lakes region of East Africa. Widespread reports of declining yields in Uganda since the 1930s and the low yields today do raise serious sustainability and food security concerns , especially as food demand increases with a population growth rate of 3.2% per annum . In addition, increasing urbanization continues to increase pressure on the banana system s, with bunches and leaves increasingly transported from rural areas to urban centres, leading to the continued loss of nutrients especially potassium. Actual yields on many smallholder banana farms (5 − 20 Mg ha − 1 yr − 1 FW ) in Uganda are far below the estimated potential yield (100 Mg ha − 1 FW ). Farmers cite soil fertility decline, pests ( banana weevils and nematodes) and moisture stress as the major factors responsible for yield decline. In response, several organic and mineral fertilization experiments have been carried out at research stations and in farmers’ fields in Uganda since the 1950s . Researchers have mostly reported responses to organic fertilizers, no or poor responses to Mg and P fertilization with some responses to K and N fertilization , but with yields that are far below the estimated potential . Although pests are controlled in so me trials, researchers have often failed to embrace a systems approach , quite often leaving out factors, such as moisture stress and soil physical conditions that affect the responses to fertilization . The government of Uganda in the National Development Plan 2010/11−2014/15 targets increased agricultural productivity for key staple crops like bananas in alleviating poverty in rural areas and ensuring national food security. In order to set proper banana research priorities to benefit farmers in Uganda , the objectives of this study were : to review past research aimed at reducing banana production constraints , identify opportunities and challenges facing the banana sector and put forward new research perspectives .

Manejos de cobertura, mecanismos sulcadores e velocidades de operação sobre a semeadura direta da cultura do milho

A palhada de cobertura residual representa o grande diferencial do sistema de semeadura direta, propiciando melhorias nas condições biológicas, químicas e físicas do solo, em contrapartida esta matéria seca residual pode implicar em dificuldades no processo de semeadura, necessitando por vezes de um manejo deste resíduo. O presente trabalho teve por objetivo avaliar o desenvolvimento e produtividade da cultura do milho submetido a diferentes métodos de manejo de palhada, mecanismos sulcadores e velocidades de operação. Utilizou-se o delineamento em blocos ao acaso com parcelas subsubdivididas, composto por 16 tratamentos e quatro repetições, totalizando 64 unidades experimentais. Os tratamentos foram compostos pela combinação entre quatro manejos de palhada (palha gradeada, rolada, triturada e dessecada), dois mecanismos sulcadores (disco duplo e haste sulcadora) e duas velocidades de semeadura (4,5 e 7,0 km h-1). Avaliou-se a profundidade de deposição de sementes, área de solo mobilizada, uniformidade de distribuição de sementes, estande inicial de plantas, número de fileiras por espiga, número de grãos por fileira, massa de mil grãos e produtividade da cultura. Os dados obtidos foram submetidos às análises de variância e havendo diferenças significativas, as médias foram comparadas pelo teste de Tukey, a 5% de significância. A velocidade de operação de 7,0 km h-1 apresentou valores de espaçamentos falhos e duplos mais elevados. Os tratamentos empregados não influenciaram os componentes de rendimento da cultura, bem como não se observou diferenças significativas para a produtividade média da cultura de milho.

Phenology shift from 1989 to 2008 on the Tibetan Plateau: an analysis with a process-based soil physical model and remote sensing data

Phenology is critical to ecosystem carbon quantification, and yet has not been well modeled considering both aboveground and belowground environmental variables. This is especially true for alpine and pan-arctic regions where soil physical conditions play a significant role in determining the timing of phenology. Here we examine how the spatiotemporal pattern of satellite-derived phenology is related to soil physical conditions simulated with a soil physical model on the Tibetan Plateau for the period 1989-2008. Our results show that spatial patterns and temporal trends of phenology are parallel with the corresponding soil physical conditions for different study periods. On average, 1 °C increase in soil temperature advances the start of growing season (SOS) by 4.6 to 9.9 days among

Soil physical conditions limit palm and tree basal area in Amazonian forests

Background: Trees and arborescent palms adopt different rooting strategies and responses to physical limitations imposed by soil structure, depth and anoxia. However, the implications of these differences for understanding variation in the relative abundance of these groups have not been explored. Aims: We analysed the relationship between soil physical constraints and tree and palm basal area to understand how the physical properties of soil are directly or indirectly related to the structure and physiognomy of lowland Amazonian forests. Methods: We analysed inventory data from 74 forest plots across Amazonia, from the RAINFOR and PPBio networks for which basal area, stand turnover rates and soil data were available. We related patterns of basal area to environmental variables in ordinary least squares and quantile regression models. Results: Soil physical properties predicted the upper limit for basal area of both trees and palms. This relationship was direct for palms but mediated by forest turnover rates for trees. Soil physical constraints alone explained up to 24% of palm basal area and, together with rainfall, up to 18% of tree basal area. Tree basal area was greatest in forests with lower turnover rates on well-structured soils, while palm basal area was high in weakly structured soils. Conclusions: Our results show that palms and trees are associated with different soil physical conditions. We suggest that adaptations of these life-forms drive their responses to soil structure, and thus shape the overall forest physiognomy of Amazonian forest vegetation.

Residence times of woody biomass in tropical forests

Background: The woody biomass residence time (τw) of an ecosystem is an important variable for accurately simulating its biomass stocks. Methods and results: We reviewed published data from 177 forest plots across the tropics and found a six-fold variation (23–129 years) in τw across our dataset, with a median τw of ca. 50 years. This value is similar to the median default value across 21 vegetation models for tropical forests, although the range of values used in models is large (20 to 200 years). Conclusions: The notion of a constant τw across all tropical forests may be of limited utility, given the large observed variation in τw. We found that while there was little relationship between climate variables and τw, there was evidence that edaphic factors exerted a strong influence on τw. In both the Neotropics and the Paleotropics, τw was highest in heavily weathered soils, suggesting that low soil fertility and/or non-limiting soil physical conditions exert a critical influence on τw. There is considerable uncertainty in how τw will be affected by global environmental change, especially by increased atmospheric CO2. Even small changes in τw could significantly reduce the future tropical forest carbon sink predicted by many vegetation models.

Effect of sheep and cattle treading damage on soil microporosity and soil water holding capacity

With the recent introduction of a large scale district irrigation scheme into the North Otago Rolling Downlands (NORD) of New Zealand, land use has intensified including a shift from dryland sheep farming to irrigated dairying. Land use change and intensification has lead to considerably greater physical pressure on soils and has been associated with a decline in soil physical condition. A farmlet trial was established in the NORD to compare the influence of four farm management systems; cattle irrigated, cattle dryland, sheep irrigated and sheep dryland on soil structure. Soil compaction under irrigated cattle grazed pasture caused a significant decline in readily available water (RAW) relative to all other treatments. A decline in total porosity and pore size indicated a lower irrigation volume applied more frequently will be required to maintain soil matric potential between irrigation trigger point (−100kPa) and field capacity (−10kPa). Changes in soil water release characteristics under animal grazing may also limit the rate of natural soil structural recovery thereby increasing the risk of repeated soil damage with on-going grazing, particularly under cattle irrigated pasture, where the initial damage was most severe.

Use of rice husk to enhance peach tree performance in soils with limiting physical properties

This study evaluated the use of rice husk as an amendment in a soil with limiting physical conditions. The research was conducted in a commercial peach orchard planted in 2011 using a ridge planting system. Six soil and water management treatments were evaluated in 18 experimental units, which were set up in the field using a randomized complete block design. The treatments were compared both in terms of soil physical condition effects and crop response. Localized substrate amendment of the soil significantly increased both saturated hydraulic conductivity and aeration porosity by 90-fold and 76%, respectively, compared with unamended treatments. In the case of growth parameters, amended trees presented the highest overall values without affecting crop water status. In terms of canopy ratio (CR), the amended treatment produced the highest overall value (0.56m2m−3), a 44% increase compared to control treatment. Localized soil amendment with rice husk contributed to both peach tree performance and residue management.

Water and Bromide Dynamics in a Soil Amended with Different Urban Composts

Urban waste compost additions to soil can increase soil organic matter content and improve soil physical conditions, leading to agronomic and environmental benefits. The need for information still exists to evaluate more precisely the effects of urban waste compost on soil physical properties. Three types of urban waste composts, a biowaste compost (BIO), a municipal solid waste compost (MSW), and a co‐compost of green waste and sewage sludge (GWS), were applied once every 2 yr on a loamy soil for 10 yr. The effects of the three composts on soil water and solute transport dynamics were tested. Soil water matric head and water content were monitored using tensiometers and time domain reflectometry probes, respectively. A Br− tracer experiment was also conducted to evaluate the effect of compost application on nonsorbing solute transport. Water content measurements showed that the application of composts significantly (P < 0.05) affected soil water content in the plow layer, with average increases of 0.03 cm3 cm−3 for the GWS and MSW compost, and 0.015 cm3 cm−3 for the BIO compost compared with a control without organic amendment. Bromide tracing during the wetting period showed that the application of urban waste composts did not affect the soil's potential for leaching. The application of composts did reduce soil evaporation during the spring, however, which in turn favored downward Br− migration in the soil.

A review of the soil science research legacy of the triumvirate of cotton CRC

For nearly two decades (1994–2012) a series of three consecutive Cooperative Research Centres (CRC) dealing with cotton production provided the impetus and financial support for a substantial body of soil science research in eastern and northern Australia. Focusing on the most commonly utilised soil for irrigated crop production, the Vertosol, CRC-affiliated soil researchers undertook detailed soil inventories of cotton-growing valleys in New South Wales, and tackled a range of applied soil research questions that faced the entire Australian cotton industry. Across the broad categories of soil mapping and characterisation, soil physical condition, salinity and sodicity, soil chemical fertility, and soil carbon and biota, some 120 CRC-affiliated research papers were published in peer-reviewed journals during the years of the CRC. Findings from this body of research were fed back to the industry through conferences, extension workshops and materials, and to a lesser extent, the peer-reviewed publications. In certain cases, underpinning basic research was carried out concurrently with the more applied research, meaning that the cotton CRC were effectively supporting advances in the discipline of soil science, as well as in sustainable cotton production. A feature of the soil research portfolio over the span of the three cotton CRC was that priorities shifted according to the interplay of three factors; the natural maturation of research topics and the concomitant evolution of cotton farming systems, the rising importance of environmental implications of agricultural land use, and the emergence of carbon as a national research priority. Furthermore, the commitment of the CRC to education resulted in the involvement of undergraduate and postgraduate university students in all aspects of the soil research effort. A legacy of the triumvirate of cotton CRC is a wide-ranging body of both applied and basic knowledge regarding the physical, chemical and biological attributes of Australian Vertosols used for irrigated agriculture.

Spatial variability and estimate of critical sites for bulk density in an oxisol

The soil physical condition is complex and must be analyzed in terms of a set of specific indicators and their inter-relations. This work aimed to evaluate the spatial variability of bulk density and related effects from other physical attributes in an experimental area of Oxisol in order to detect and estimate sites with critical values for root development. Linear models were fitted to the spatial bulk density in layers 0-0.2 and 0.2-0.4 m, considering the Gaussian process. Models were adjusted with and without a principal component, and models containing the covariate density in the previous layer to depth of 0.2-0.4 m. Performed kriging, probability maps to obtain bulk density above 1.4 kg dm-3 were constructed based on 1000 simulations from predictive distribution. There were sites with critical values of soil density. There were no related effects of moisture, sand, silt and clay in the bulk density levels, however, it was no influence from upper layer in the layer density levels on 0.2-0.4 m. There was evidence of sites over 80% probability of occurrence of critical levels of bulk density, in the two layers.

The effect of sodicity on cotton: Does soil chemistry or soil physical condition have the greater role?

Soil sodicity is widespread in the cracking clays used for irrigated cotton (Gossypium hirsutum L.) production in Australia and worldwide and sometimes produces nutrient imbalances and poor plant growth. It is not known whether these problems are due primarily to soil physical or to soil chemical constraints. We investigated this question by growing cotton to maturity in a glasshouse in large samples of a Grey Vertosol in which the exchangeable sodium percentage (ESP) was adjusted to 2, 13, 19, or 24. A soil-stabilising agent, anionic polyacrylamide (PAM), was added to half the pots and stabilised soil aggregation at all ESPs. Comparison of the effect of ESP on cotton in the pots with and without PAM showed that, up to ESP of 19, the soil physical effects of sodicity were mainly responsible for poor cotton performance and its ability to accumulate potassium. At ESP >19, PAM amendment did not significantly improve lint yield, indicating that soil chemical constraints, high plant sodium concentrations (>0.2%), and marginal plant manganese concentrations limited plant performance. Further research into commercial methods of amelioration of poor physical condition is warranted rather than application of more fertiliser.

Improvements in geophysical surface soil assessment and classification using modifying Jenny’s equation of soil forming factors in the Sudan Savannah

Assessment and classification of agricultural surface soil in the Sudan Savannah, Kebbi State Nigeria was carried out from 2008 to 2011 using a modified version of Jenny's equation of soil forming factors. A comprehensive account of major classes of surface soil characteristics was given. The following surface soil components have been covered: temperature and moisture characteristics, topography, parent materials, organisms and land properties. Consequently, the physical agricultural surface soil conditions in five local government areas of the State: Arewa, Argungu, Augie, Birnin-Kebbi and Dandi are characterised by six major surface moisture characteristics: aquic, aridic, torric, udic, ustic and perudic; 10 topographical classes: back- slope, bendy, concave, contour, convex, deeply,flatly, linear-flat and shallow; three major soil biota: ants, earthworms and termites; andseven land characteristics: bad-lands, blown-out-lands, cirque-lands, fertile- lands, gulliedlands, miscellaneous and rock-outcrops. The major parent materials are alluvial, colluvial,fluvial and lacustrine. Physically, these parent materials are describe according to theirphysical appearance into fadama clay soils, fadama clay-loam soils, dryland sandy soils,dryland sandy-loam soils, dryland stony soils, and organic-mineral soils. Generally, the studyhas provided a better understanding of the current status of the major physical components ofagricultural soils and overall natural environment for future agricultural economic management in the region.

Multivariate Analysis of Data on the Effects of Different Vegetative Covers on Some Physical Properties of a Selected Nigerian Soil

This work discusses the use of multivariate analysis of variance to tackle the problem of investigating the effects of different vegetative covers on the physical properties of a selected Nigerian soil. An additive effect model was assumed and using data obtained from the Department of Soil Science of the University of Nigeria, Nsukka, we tested for the equality of significant treatment effects. The result of the analysis revealed that the treatment effects were found to be significant being acceptable at 5 percent level. Based on our analysis, we recommended that the vegetative covers in question are useful and necessary and therefore should be used to improve the soil physical conditions for any overused land in Nsukka area of Nigeria and similar soils elsewhere not in Nsukka depending on the use and type of farming system the land is put to.

Seeding quality and soybean yields from using different furrowers and operation speeds

Em culturas anuais submetidas ao sistema plantio direto o processo de semeadura afeta o condicionamento físico do solo ao redor das sementes expondo as mesmas a condições adversas, podendo limitar o desenvolvimento inicial das plantas e minimizar o potencial produtivo. O uso de sulcadores não condizentes com a situação de campo e de velocidades inadequadas são fatores que afetam o bom desempenho da semeadura. Nesse contexto, este trabalho teve por objetivo, avaliar o efeito de diferentes sulcadores e velocidades de operação sobre parâmetros de qualidade de semeadura e componentes de produtividade da cultura da soja. Os tratamentos foram compostos pela combinação entre dois sulcadores (disco e haste) e quatro velocidades de operação (0,86; 1,22; 1,47 e 1,94 m s-1). Foram avaliados: o número médio de dias para a emergência, a uniformidade de distribuição de plantas, a profundidade de semeadura, a área de solo mobilizado, o estande de plantas e a produtividade de grãos. De acordo com os resultados, o sulcador tipo haste proporcionou maior profundidade de semeadura e área de solo mobilizada, quando comparado ao disco duplo defasado. O aumento da velocidade reduziu o estande de plantas e a produtividade da cultura e aumentou a área de solo mobilizada.