Contribution Of Soil Properties Research Articles

Long-term integrated soil-crop management improves soil microbial community structure to reduce GHG emission and increase yield.

Integrated soil-crop management (ISCM) has been shown as an effective strategy to increase efficiency and yield while its soil microbial community structure and function remain unclear. We evaluated changes in soil physicochemical factors, bacterial community structure responses, and the contributions of soil properties and bacterial communities to summer maize-winter wheat yield and GHG emissions through an ISCM experiment [T1 (local smallholder farmers practice system), T2 (improved management system), T3 (high-yield production system), and T4 (optimized management system)], which could provide scientific guidance for sustainable development of soil in summer maize-winter wheat rotation system. The results showed that the optimized ISCM could improve the soil quality, which significantly changed the soil bacterial community structure to reduce GHG emissions and increase yield. The co-occurrence network density of T3 was increased significantly. The Acidobacteria (class) and OM190 (class) were enriched in T2 and T4. The Frankiales (order) and Gaiellales (order) were enriched in T3. However, the changes in different crop growth stages were different. At the wheat jointing stage and maize mature stage, T4 could enhance carbon-related functional groups, such as aromatic hydrocarbon degradation and hydrocarbon degradation, to increase the soil organic carbon content. And at the maize tasseling stage, T4 could enhance nitrogen-related functional groups. And soil bacteria structure and function indirectly affected annual yield and GHG emission. T2 and T4 exhibited a similar soil microbial community. However, the yield and nitrogen use efficiency of T2 were reduced compared to those of T4. The yield of T3 was the highest, but the GHG emission increased and soil pH and nitrogen use efficiency decreased significantly. Therefore, T4 was a suitable management system to improve soil quality and soil bacterial community structure and function to decrease GHG emissions and increase the yield of the summer maize-winter wheat rotation system.

Short-term but not long-term perennial mugwort cropping increases soil organic carbon in Northern China Plain.

Perennial cropping has been an alternative land use type due to its widely accepted role in increasing soil carbon sequestration. However, how soil organic carbon (SOC) changes and its underlying mechanisms under different cropping years are still elusive. A chronosequence (0-, 3-, 6-, 20-year) of perennial mugwort cropping was chosen to explore the SOC dynamics and the underlying mechanisms in agricultural soils of Northern China Plain. The results revealed that SOC first increased and then decreased along the 20-year chronosequence. The similar patterns were also found in soil properties (including soil ammonium nitrogen, total nitrogen and phosphorus) and two C-degrading hydrolytic enzyme activities (i.e., α-glucosidase and β-glucosidase). The path analysis demonstrated that soil ammonium nitrogen, total nitrogen, and plant biomass affected SOC primarily through the indirect impacts on soil pH, total phosphorus availability, and C-degrading hydrolytic enzyme activities. In addition, the contributions of soil properties are greater than those of biotic factors (plant biomass) to changes in SOC across the four mugwort cropping years. Nevertheless, the biotic factors may play more important roles in regulating SOC than abiotic factors in the long run. Moreover, SOC reached its maximum and was equaled to that under the conventional rotation when cropping mugwort for 7.44 and 14.88 years, respectively, which has critical implications for sustainable C sequestration of agricultural soils in Northern China Plain. Our observations suggest that short-term but not long-term perennial mugwort cropping is an alternative practice benefiting soil C sequestration and achieving the Carbon Neutrality goal in China.

Decomposition dynamics and driving factors of manure in reclaimed soils in coal mining area

Understanding the decomposition dynamics and driving factors of manure in the soil subjected to different reclaimed years could provide theoretical basis to rational utilization of manure and soil fertility improvement in coal mining area. Cattle manure and pig manure were mixed with soils subjected to different reclaimed years (one year, R1; 10 years, R10; and 30 years, R30) at the ratio of manure carbon to soil mass of 4 to 100, so as to examine manure decomposition characteristics using the nylon mesh bag (15 cm deep of soil buried) in the Shanxi coal mine reclamation area, with no manure addition as control (CK). Soil samples were collected at day 12, 23, 55, 218, 281, and 365 to measure the contents of soil manure residual, soil microbial biomass carbon (MBC), and dissolved organic carbon (DOC). The contributions of soil properties, manure properties, and hydrothermal condition to manure decomposition were quantified. The results showed that the decomposition rates of pig manure were significantly higher than cattle manure. The humification coefficient of pig manure (average 46.3%) was lower than that of cattle manure (average 71.7%). The humification coefficient of pig manure was significantly lower in the 30-year reclaimed soil (44.5%) compared to the 1-year and 10-year reclaimed soil (average 47.2%). There was no significant difference in the humification coefficient of cattle manure among the three reclaimed soils. The proportion and decomposition rate constant of labile carbon pool of pig manure and cattle manure were significantly different, with values of 52% and 26%, and 0.00085 and 0.00074 ℃-1, respectively. The positive effect of pig manure on MBC and DOC in reclaimed soil was significantly higher than that of cattle manure over 0-218 days, but no difference over 281-365 days. The magnitude of the enhancement of MBC and DOC in those three reclaimed soils after manure amendments showed a similar trend of R1 >R10 ≈ R30. Results of variance partitioning analysis showed that manure decomposition was mainly controlled by manure properties (17.9%) when considering soil properties, manure properties, and hydrothermal condition. In conclusion, the decomposition of pig manure but not cattle manure was regulated by reclamation year. Cattle manure, with higher humification coefficient than pig manure, was recommended for reclaimed mining area to improve soil fertility.

Impact of urbanization on soil microbial diversity and composition in the megacity of Shanghai

AbstractUrbanization alters the physicochemical environment on an unprecedented scale and strongly affects biodiversity. How urbanization affects the biodiversity of soil microbial communities, especially in large cities, however, is poorly known. We investigated soil microbial communities from 258 sites covering a variety of environmental gradients in the megacity of Shanghai, China, to determine the impact of urbanization on soil microbial biodiversity. Using the distance to city centre, urbanized land cover, and road density as three proxies to characterize the levels of urbanization, we revealed that increased urbanization was associated with slightly homogenized communities of prokaryotes, total fungi, and arbuscular mycorrhizal fungi but not ectomycorrhizal fungi. The richness of soil prokaryotes and total fungi was weakly but positively related to urbanization as well. For the abundance of microbial phylotypes along urban gradients, we observed synchronous increases and decreases of many phylotypes at relatively high and low urbanization levels, respectively. Further, urbanization explained an independent part of microbial variances in richness and community composition, although the contribution of soil properties in explaining the variances was generally larger than that of urbanization. Together, this work provides evidence for the influences of urbanization on the biodiversity of soil microbes and highlights the importance of considering taxa and the level of urbanization to assess the impacts of urbanization on biodiversity.

Long-term organic fertilizer substitution increases rice yield by improving soil properties and regulating soil bacteria

Applying organic and inorganic fertilizers together could sustainably increase crop yields. The effects of long-term organic fertilizer substitution on soil microbial community structure and function in paddy soil and on rice yield remain unclear. We evaluated changes in soil physicochemical factors, bacterial community structure responses, and the contributions of soil properties and bacterial communities to rice yield after 34 years of different fertilization treatments. A high ratio of organic fertilizer substitution significantly reduced soil acidification, improved soil nutrients, and increased soil urease and catalase activities (P < 0.05). Organic fertilizer substitution significantly changed the soil bacterial community structure and increased the relative abundance of beneficial bacteria, such as Bacilli and Flavobacteriales. The highest proportion of organic substitution treatment significantly enhanced carbon-related functional groups (P < 0.05), like aromatic hydrocarbon degradation and chitinolysis. The biomarkers enriched in the inorganic treatment and the organic fertilizer substitution treatments had similar correlated environmental factors but opposite correlation trends. Soil nutrient levels, especially total nutrients, explained most of the variation in annual rice yield, while bacteria indirectly affected annual yield through enzyme activities and nutrient levels. Our results provide evidence that soil nutrients and bacteria contribute to rice yield increase in long-term organic fertilizer substitution treatment.

Using manure for improving nitrogen fertilization and maize yield

AbstractManure and chemical fertilizers have different effects on soil properties, the nitrogen cycle, and crop yield. This study aimed to investigate the effects of different fertilizer applications under the same N input on soil physicochemical properties and soil bacterial communities and to explain the contributions of soil properties to grain yield. Manure substitution of chemical fertilizer was conducted in leaching monitoring systems. The study began in 2009 and sampling was carried out in 2014 and 2016. Three fertilizer treatments with the same total N, P, and K application rates and one control treatment were designed as follows: (1) CK, without nitrogen fertilizer; (2) 100%U, whole nitrogen coming from urea; (3) 100%M, whole nitrogen coming from composted cattle manure; and (4) 50%U + 50%M, half nitrogen from composted cattle manure and half nitrogen from urea. Soil organic carbon (SOC) content was positively correlated with total N (TN), NO3−–N, and NH4+–N contents, the mean weight diameter of soil aggregates, and the Shannon diversity index of bacteria, whereas SOC content was not significantly correlated with grain yield. NO3−–N content was positively correlated with grain yield. Substituting half the amount of chemical fertilizer with manure as a nitrogen source improved soil stability, increased bacterial diversity, and enhanced nitrogen supply, while reducing nitrogen loss from ammonia volatilization and nitrogen leaching. Substituting half the amount of chemical fertilizer with manure as a nitrogen source was a more sustainable way to increase grain yield through a sustainable nitrate supply and to reduce N loss.

Phylogeny and distribution of arbuscular mycorrhizal fungi associated with Vachellia tortilis ssp. raddiana in relation to soil properties under arid ecosystems of Tunisia

It is of interest to investigate the diversity of arbuscular mycorrhizal fungi (AMF) associated with Vachellia tortillis ssp. raddiana to provide insights into the contribution of soil properties in shaping the AMF community composition and to define new strains for the production of inoculants under arid climate. A total of 230 symbiotic AMF clones associated with native V. tortilis roots growing in arid Tunisian soils were analyzed using nested PCR, cloning, and sequencing of the rDNA 18S region. The differential effects of soil properties on the diversity and community composition and distribution were also carried out. Phylogenetic analyses of four representative clones’ libraries grouped them into nine AMF operational taxonomic units (OTUs) among the Glomeraceae family. Two OTUs (OTU4 and OTU7) were separated from any AMF reference sequence and may constitute new species within the Glomeraceae. The distribution pattern under soil properties showed that high available phosphorus content in the soil and electric conductivity decrease AMF diversity and that the remaining soil parameters are correlated with the AMF community composition. Specific soil properties associated with the diverse relative distribution of AMF species, described for the first time in this work, may serve as a model for studying how spatially distributed AMF in a wide range of habitats may be utilized by a pioneering plant with a situation that is frequently occurring at reclaimed sites or in ameliorated soils when a new vegetation cover such as Vachellia sp. needs to be established.

Groundwater depth as a constraint on the woody cover in a Neotropical Savanna

Aims To identify the role of soil properties and groundwater depth on the structure of a fire-protected neotropical savanna. We aimed to address: i) What is the contribution of soil properties and groundwater depth to the physiognomic variation? ii) Are these factors associated with patterns in woody structure? iii) Are open physiognomies maintained by shallow groundwater?

Spatial Variability of Grapevine Bud Burst Percentage and Its Association with Soil Properties at Field Scale

There is a growing interest in precision viticulture with the development of global positioning system and geographical information system technologies. Limited information is available on spatial variation of bud behavior and its possible association with soil properties. The objective of this study was to investigate spatial variability of bud burst percentage and its association with soil properties based on 2-year experiments at a vineyard of arid northwest China. Geostatistical approach was used to describe the spatial variation in bud burst percentage within the vineyard. Partial least square regressions (PLSRs) of bud burst percentage with soil properties were used to evaluate the contribution of soil properties to overall spatial variability in bud burst percentage for the high, medium and low bud burst percentage groups. Within the vineyard, the coefficient of variation (CV) of bud burst percentage was 20% and 15% for 2012 and 2013 respectively. Bud burst percentage within the vineyard showed moderate spatial variability, and the overall spatial pattern of bud burst percentage was similar between the two years. Soil properties alone explained 31% and 37% of the total spatial variation respectively for the low group of 2012 and 2013, and 16% and 24% for the high group of 2012 and 2013 respectively. For the low group, the fraction of variations explained by soil properties was found similar between the two years, while there was substantial difference for the high group. The findings are expected to lay a good foundation for developing remedy measures in the areas with low bud burst percentage, thus in turn improving the overall grape yield and quality.

Levels and Potential Sources of Heavy Metals in Major Irrigated Rice Areas of the Philippines

Industrialization, urbanization and intensive use of farm inputs can pollute agricultural areas. The study was then conducted to assess the levels of chromium (Cr), nickel (Ni), copper (Cu), cobalt (Co), zinc (Zn), arsenic (As), molybdenum (Mo), cadmium (Cd), mercury (Hg), and lead (Pb) in the country’s major rice areas. The study also determined the contributions of soil properties, land uses, irrigation water, and farm inputs to the metal levels. Strategic collections of soil, plant and water samples in the country’s major soil series planted to rice, analyses of samples using x-ray fluorescence or atomic absorption spectroscopy, and farmer interviews were done. Metal levels were very high in Zambales and Negros Occidental soils due to deposition or use of metal-enriched mine tailings and irrigation water. Soil metal concentrations in Zambales far exceeded the intervention values of 180 mg/kg for Cr and 100 mg/kg for Ni. Soil metal levels in Negros Occidental exceeded the intervention value of 190 mg/kg for Cu and Mo. Rice plants in Negros Occidental exceeded the toxic levels of 30 mg/kg for Cu and 10-50 mg/kg for Mo due to the very high soil Cu and Mo concentrations in the area. Molybdenum concentrations of rice plants in Sultan Kudarat and Camarines Sur exceeded the toxic level due to the high amounts of foliar chemicals applied at &gt;66 sprayer loads per year. The study implies that rice areas deposited with mine wastes have high heavy metal levels, and foliar chemicals can increase metal levels in rice. Keywords - Environmental toxicology, heavy metals, heavy metal sources, rice soils, Philippines

Levels and sources of potassium, calcium, sulfur, iron and manganese in major paddy soils of the Philippines

Nutrient levels in rice areas can be translated to the soils’ capacity to supply the essential elements for rice, while information about nutrient sources can be used to formulate management options to areas deficient or toxic in nutrients. This study was then conducted to assess the potassium (K), calcium (Ca), sulfur (S), iron (Fe) and manganese (Mn) levels in the Philippines’ major rice areas. The study also determined the contributions of soil properties, land uses, irrigation water, and farm practices to the nutrient levels. Strategic collection of soil and plant samples, laboratory analyses of samples, and farmer interviews were done. Potassium concentrations of rice plants in La Paz (Tarlac) and Sta. Rosa City (Laguna) exceeded the toxic concentration of 3%. These K concentrations can be due to the increase of the nutrient’s availability owing to the neutral soil pH levels in the two sites. The highest total Ca levels were found in the Polangui (Albay), La Paz, and Villasis (Pangasinan) soils. These Ca levels can be ascribed to the occurrence of Ca in sand and silt-sized soil fractions. Total Fe and Mn concentrations were very high in the Sta. Cruz (Zambales) soil due to the input of mine wastes. The San Leonardo (Nueva Ecija) soil’s high total Fe concentration is probably due to the occurrence of Fe in clay-sized soil fractions. Iron and Mn levels of rice in most Central Luzon sites exceeded the toxic concentrations of 1000 mg kg-1 for Fe and 300 mg kg-1 for Mn. These concentrations can be due to the high total soil Fe and Mn levels, and their increased plant uptake due to periodic soil submergence and increased soil acidity from continuous cropping. The study implies that K, Ca, Fe and Mn are enriched in rice areas due to soil properties and farm practices. Keywords—potassium, calcium, sulfur, iron, manganese, paddy soils

CONCENTRATION AND DISTRIBUTION OF IRON AND MANGANESE FRACTIONS IN ALABAMA ULTISOLS

Information on metal forms and contributions of soil properties on metal distribution in Alabama soils is either limited or meager. This study chemically partitioned and evaluated soil Fe and Mn distributions and applied stepwise multiple regressions to identify the soil properties influencing their distributions in some Alabama Ultisols. Iron and Mn distributions among metal fractions were generally dependent on total metal content, soil properties, and degree of chemical weathering. Distributions among metal fractions showed that Fe was mainly in the residual fraction (> 85%), whereas Mn was predominantly oxide-bound and in the residual fraction (> 90%). The proportion of Fe fractions in the soils was in the order: residual > oxides (crystalline FeO, amorphous FeO, MnO) > organic > exchangeable, whereas Mn was in the order: oxide-bound (MnO, amorphous FeO, crystalline FeO,) > residual > exchangeable > organic fraction. Stepwise multiple regression analysis showed that pH accounted for 33% of the total variability in exchangeable Fe, whereas SOM accounted for 47.1% of the total variability in exchangeable Mn. Clay and sand contents accounted for 42.2 and 52.3%, respectively, of the total variability in the residual Fe fraction, whereas silt accounted for 19.7% of the total variability in residual Mn distribution in these soils.

Soil Fertility Status and Cassava Yield in Tanzania: (II) Contributions of Soil Properties to Cassava Yield Variations

During the Collaborative Study of Cassava in Africa (COSCA) survey, cassava yields and soil samples were obtained from farmers' fields in order to assess the yield levels and the contributions of soil properties to variations in such yield parameters as fresh root and shoot, harvest index and stand density. The average root yield was estimated as 10.5 t/ha, harvest index averaged about 0.50 and stand density was about 64,000 per hectare. Both the root and stand density had coefficients of variation above 150%. Each of the yield parameters correlated with at least 13 of the 28 soil properties considered in the simple correlation analysis carried out. The variations in the yield parameters were attributed to the differences in such agro-ecological factors as climate, altitude and soil properties. The contribution of soil variables to the variations in all the yield parameters was more than 80% in all cases. The most important variables were N:P ratio for root yield, clay content for shoot yield, OM content for harvest index and exchangeable Mn for stand density. This analysis indicates that in relating root yield to nutrient levels, nutrient ratios should also be considered because the absolute values of each nutrient may not be the only determining factor.