Dynamics of maize straw–derived nitrogen in soil aggregates as affected by fertilization

Journal of Soils and Sediments - The addition of maize residue nitrogen (N) to the soil strongly influences soil N accumulations, but the specific contributions of maize residue N to soil...     

Sorption–desorption of phenolic acids as affected by soil properties

Phenolic acids have been implicated in the process of allelopathy and are, therefore, of interest in plant management as a basis for new herbicide structures. The potential bioavailability of phenolic acids is controlled by sorption–desorption processes in soil. Sorption–desorption of p-coumaric acid (4-hydroxycinnamic acid), ferulic acid (3-methoxy-4-hydroxycinnamic acid), veratric acid (3,4-dimethoxybenzoic acid), vanillic acid (3-methoxy-4-hydroxybenzoic acid), and p-hydroxybenzoic acid (4-hydroxybenzoic acid) was characterized on soils with varying physicochemical properties. The phenolic acids sorbed quickly (<8 h) and in high proportions to the amount applied (average 84% of applied was sorbed). Sorption was irreversible with the batch desorption method used (0.01 N CaCl₂ extraction). Pretreatment of soils to remove organic matter and free metal oxides from the soils decreased sorption, particularly in soils with free oxides removed. Statistical analysis suggested that sorption of p-coumaric and ferulic acids was correlated with soil clay content and veratric acid sorption was correlated with several soil factors. In contrast, no consistent relationship between soil characteristics and vanillic and p-hydroxybenzoic acid sorption was found. Based on the results of these experiments, i.e. the high reactivity of the phenolic acids, it is unlikely that these chemicals would be transported far from their point of origin, limiting their range of influence. It appears that, for phenolic acids to have allelopathic effects on plants, they would have to persist in the soil for long periods, resulting in a buildup of the chemical to high enough levels so that sufficient chemical would be in solution to cause the allelopathic effects, even though they may be strongly sorbed at lower concentrations.     

Effects of freeze–thaw cycles and the soil water content on carbon and nitrogen changes in different soil types of Heilongjiang Province,China

To reveal the influence of freeze–thaw cycles (FTCs) on soil carbon and nitrogen changes, six typical soils in Northeast China were selected as the research objects to conduct a FTC simulation test in an artificial climate chamber. Three soil volumetric water contents (10%, 20%, 30%) and eight FTCs (0, 2, 4, 6, 8, 10, 15, 20) were set. The results showed that the soil organic carbon (SOC) and microbial biomass carbon (MBC) contents of different soil types under the FTCs initially exhibited a downward and then an upward trend, while the dissolved organic carbon (DOC) content exhibited an upward and then a downward trend. Otherwise, the fourth and sixth FTCs were the key points of change. The SOC, MBC and DOC contents in paddy fields were higher than those in dry fields, showing upward and then downward trends spatially from northeast to southwest. The SOC and MBC contents in each soil type were the highest at the 20% water content, and the DOC content gradually increased with increasing water content. The ammonium nitrogen (NH₄⁺-N) content in different soil types at different water contents under the FTCs showed an upward trend first, then a downward trend and finally an upward trend. The NH₄⁺-N content in paddy fields was higher than that in dry fields. The nitrate nitrogen (NO₃^‒-N) content showed a downward trend first, then an upward trend and finally a downward trend. The NO₃^‒-N content in dry fields was higher than that in paddy fields. The NH₄⁺-N contents in the three soil types on the Sanjiang Plain were significantly higher than those on the Songnen Plain. The NH₄⁺-N and NO₃^‒-N contents showed upward trends with increasing water content, but the differences were not significant. The results have implications for the study of different types of soils and provide references for research on the mechanism of soil carbon and nitrogen transformation in typical farming areas in Northeast China.     

Soil organic carbon as affected by direct drilling and mulching in sugar beet – wheat rotations

The effect of conventional ploughing, mulching, and direct drilling on the soil organic C (soil C_org) contents through the soil profile and on total soil C_org stocks (0–45 cm) was investigated at five different German sites. All sites showed similar results: after 10–13 years, soil C_org contents in the surface soil (0–10 cm) were 15–71% and 33–42% higher under direct drilling and mulching, respectively, than under ploughing (8–18 g kg^?1). Under ploughing, the soil C_org contents were distributed homogenously through the soil profile. Either mulching or direct drilling resulted in 3–28% higher soil C_org stocks than ploughing (49–116 t ha^?1). However, the tillage management was no significant factor since the sites showed the effects to different extents but were the mathematical replications. Five to six years later, trends and values were similar. We concluded that the main effect of mulching or direct drilling was the stratification with higher soil C_org contents in the surface soil. Since this is a positive means for soil protection, we suggested that the use of mulching or direct drilling can contribute to a sustainable soil management in crop rotations with sugar beet which are characterized by a strong physical impact on the soil during harvest.     

Variability of soil water content controlled by evapotranspiration and groundwater–root zone interaction

The central moments of soil water content (SWC) variability at the field scale are determined by soil texture, considering both smooth topography and groundwater table position. The characteristics of variability are governed by other soil factors like soil structure, micro relief, preferred water flow paths, root system characteristics, rock content, etc. This paper shows the integral effect of all these hardly quantifiable factors on SWC variability simulated by the processes of evapotranspiration and groundwater–root zone interaction using the HYDRUS ET model. SWC and soil hydraulic characteristics were spatially determined over a 4.5 ha field during two sampling campaigns under different atmospheric and groundwater conditions, and data distributions were compared to SWC distributions provided by mathematical modeling. The entire spring–summer period of 2003 was then examined for changes of SWC spatial variability. It was found that evapotranspiration influences SWC spatial variability only if SWC is under the critical value when wetter parts of the field evaporate more water than drier parts, resulting in smoothed SWC variability. Under wet conditions the spatial variability of SWC increases by drainage, as those parts of the soil with coarser texture drain faster than finer-textured parts.     

Effects of concentrated application of soil conditioners on soil–air permeability and absorption of nitrogen by young peach trees

ABSTRACT

To study the effects of concentrated application of two soil conditioners, two-year-old peach trees (Prunus persica L.‘Chunmei’) were selected to test the soil air permeability, ¹⁵N absorption and the growth of trees. The experiment comprised three treatments involved concentrated applying either polyacrylamide (treatment I) or Agri-SC (a proprietary soil conditioner, treatment II) at the bottom of each pit or neither of the two (treatment III). And then the whole pit was back-filled with soil. Neither digging a hole nor use of soil conditioners as the control (CK). The results showed that volumetric oxygen content in gases in 5–10 cm soil layer upon concentrated application layer was significantly higher in treatments I and II than that in CK. Soil volumetric water content upon concentrated application layer was higher in treatments I and II than that in CK. Compared with CK, no matter root activity, leaf area, leaf chlorophyll content, or leaf net photosynthesis rate in treatments I and II increased in August and October, which promoted the growth of new shoots and the stem. Compared with CK, the leaf superoxide dismutase activity increased 31.24%, 22.66% and 4.74%, Guaiacol peroxidase increased 21.88%, 13.25% and 3.39%, Catalase increased 11.80%, 7.92% and 1.24% respectively in treatments I, II and III in October. As a result, values of the total roots surface area, total root volume, number of root tips, dry matter accumulation, and organ nitrogen content were markedly higher in treatments I and II than that in CK. And the ¹⁵N utilization rate significantly increased 24.22% and 10.40% respectively in treatments I and II. The result suggested that concentrated application of soil conditioners formed a rhizosphere water storage and breathable layer that not only stores moisture but is also permeable to air. That, in turn, promotes plant growth, increases the nitrogen use efficiency.     

Spatial variation of soil test phosphorus and potassium,oxalate‐extractable iron and aluminum,phosphorus‐retention index,and organic carbon content in soils of Western Australia

Abstract

Spatial variation of bicarbonate soil test phosphorus (P) and bicarbonate soil test potassium (K) was studied by measuring soil test values for 40 individual soil samples collected from random locations within eight uniform 100 m by 100 m field sites in south‐western Australia. In addition, for five of the sites, spatial variation of the three P sorption indices (ammonium oxalate extractable iron, ammonium oxalate extractable aluminum, and the P retention index) and of organic carbon (C) was measured for 20 individual soils samples. Spatial variation was found to be large, with coefficient of variation (CV) exceeding 20% in most cases, and 50% in some cases. It is therefore essential to collect an adequate number of soil samples from uniform areas in paddocks in order to provide a representative composite sample to measure the soil properties.     

Soil organic phosphorus and microbial community composition as affected by 26 years of different management strategies

Agricultural management can affect soil organic matter chemistry and microbial community structure, but the relationship between the two is not well understood. We investigated the effect of crop rotation, tillage and stubble management on forms of soil phosphorus (P) as determined by solution ³¹P nuclear magnetic resonance spectroscopy and microbial community composition using fatty acid methyl ester analysis in a long-term field experiment (26 years) on a Chromic Luvisol in New South Wales, Australia. An increase in soil organic carbon, nitrogen and phosphorus compared to the beginning of the experiment was found in a rotation of wheat and subterranean clover with direct drill and mulching, while stubble burning in wheat–lupin and wheat–wheat rotations led to soil organic matter losses. Microbial biomass was highest in the treatment with maximum organic matter contents. The same soil P forms were detected in all samples, but in different amounts. Changes in organic P occurred mainly in the monoester region, with an increase or decrease in peaks that were present also in the sample taken before the beginning of the experiment in 1979. The microbial community composition differed between the five treatments and was affected primarily by crop rotations and to a lesser degree by tillage. A linkage between soil P forms and signature fatty acids was tentatively established, but needs to be verified in further studies.     

Impact of organic residues and mineral fertilizer application on soil–crop systems I: yield and nutrients content

A five-season experiment was initiated to study the effects of the recycling of some organic residues on a soil–crop system of a guar–wheat rotation in a sandy clay loam soil located in the semi-arid tropics of Sudan. Treatments included: incorporation of crop residues alone after harvest (Cr⁺), with (FCr⁺) or without (FCr^?) inorganic fertilizer, sewage sludge (SS) and humentos (H). Grain yield of wheat in FCr⁺ and Cr⁺ treatments was significantly higher than that obtained in FCr^? and control plots by ～22?62% and 116?119%, respectively. When crop residues were incorporated with inorganic fertilizer, the priming effect of crop residues on straw yield (106%) was almost double that of the priming effect of inorganic fertilizer (56%). The sustainable yield index of wheat straw dry matter for the control, crop residue, humentos, inorganic fertilizer, combined fertilizer and crop residue and sewage sludge was 28, 27, 8, 35, 21 and 38%, respectively. In general, N, P and K of straw dry matter (SDM) was in the order of FCr⁺ > FCr^? > SS > Cr⁺> H > C. The findings suggest that repeated incorporation of crop residues with inorganic fertilizer and applications of SS could both sustain wheat performance in the dryland ecosystems.     

Assessment and prediction of changes in the reserves of organic carbon in abandoned soils of European Russia in 1990–2020

Experimental studies and the analysis of published data have shown that carbon reserves in soils generally increase upon soil exclusion from agricultural use. The rate of carbon accumulation in the abandoned soils depends on the soil type, the time elapsed since the soil abandoning (the restoration period), and the thickness of the layer for which the rate of carbon accumulation is determined. For the upper 20-cm-thick layer, it varies from 66 to 175 g C/m² per year in dependence on the type of soil and averages 111 g C/m² per year. The highest rate is typical of the first 10–15 years of soil restoration. According to our calculations, the carbon sequestration in the upper 20-cm-thick layer of Russian soils due to changes in land use was 184–673 Mt C in 1990–2005 and may reach 282–1030 Mt C by 2020.     

Dry matter yield and nitrogen recovery from bromegrass in south‐central Alberta as affected by rate of long‐term nitrogen applications

Abstract

A field experiment was conducted on a Thin Black Chemozemic soil at Crossfield in south‐central Alberta to determine the effect of long‐term application of ammonium nitrate on dry matter yield (DMY), protein yield (PY), protein concentration, N use efficiency and recovery of N applied to bromegrass (Bromus inermis Leyss.) grown for hay. The N fertilizer was applied at 0, 56, 112, 168, 224, 280, and 336 kg N/ha in early spring of every year from 1968 to 1986. The DMY increased with applied N achieving a maximum at 224 kg N/ha, though the rate of increase in DMY from N fertilization was greatest with the first two increments applied (i.e. 56 and 112 kg N/ha). Protein yield and protein concentration maximized at 336 kg N/ha. The DMY was greater with a single‐cut system than with a double‐cut system. The DMY varied from year to year, but it was not closely related to precipitation received during the April to August period (R² = 0.37). However, in some years low DMYs were associated with low precipitation, or a lack of timeliness of rainfall, or a combination of both. The N use efficiency and % N recovery in bromegrass decreased with increasing N rate. The maximum DMY calculated from quadratic regressions ranged from 3.16 t/ha to 7.91 t/ha, and maximum N rate ranged from 205 to 258 kg N/ha. In summary, DMY, PY, and protein concentration increased, and N use efficiency and % N recovery decreased with increasing N rate in this 19‐year study.     

Predator–prey interaction in soil food web: functional response, size-dependent foraging efficiency, and the influence of soil texture

In a series of laboratory experiments, we presented carnivorous Macrobiotus richtersi (Tardigrada, Macrobiotidae) with nematode prey to assess their importance as predator. We investigated consumption rate for (a) different prey densities (10–400 prey individuals), (b) different prey biomasses (22–80 ng), (c) different prey species (Pelodera teres, Rhabditidae, versus Acrobeloides nanus, Cephalobidae) and (d) different environments (2-D agar surface versus 3-D sand fractions of three different textures). M. richtersi consumed up to 4.6 g nematode prey in 4 h, that is, 43% of the tardigrades body mass. Predation rate was positively correlated with prey density. The optimal prey in the present investigation was the biggest prey because it yielded the highest biomass uptake per time. In addition, the size of M. richtersi played an important role in consumption rate. Bacterivorous nematodes reacted differently to attack. Even in a water film on stiff agar where nematode agility was limited, a vigorous undulation reaction of P. teres led to a measurable reduction in consumption rate. A. nanus, in contrast, showed little response to attack. Microcosm experiments with sands of different particle size demonstrated that M. richtersi is able to chase and consume small bacterivorous nematodes in a 3-D soil matrix. However, consumption rate in sand microcosms was significantly reduced compared with pure agar. The sand matrix improved nematode agility and possibly provided small pores as refuge for the nematodes. The lowest consumption rate was observed in fine sand. Effects of predatory tardigrades on nematode numbers in the field are discussed.     

Zinc,copper, and nickel availabilities as determined by soil solution and DTPA extraction of a sludge‐amended soil

Abstract

Extracting sludge‐amended soil with DTPA does not always give a reliable measure of plant‐available heavy metals. The major purpose of this greenhouse pot study was to help explain why. Two anaerobically digested sludges from sewages treated with either Ca(OH)₂or FeCl₃were applied to 3‐kg samples of a Mollic Albaqualf previously limed with Ca(OH)₂rates of 0, 2.5, and 10g/pot that resulted in pHs in the check pots of 5.4, 6.2, or 7.7 after the first harvest. Sludge rates provided 0, 200, 40, 800, and 1600 mg Zn kg^‐1of soil. Two consecutive crops of soybeans (Glycine MaxL.) were grown for 42 d each in the greenhouse. DTPA‐extractable, soil‐solution, and plant concentrations of Cu²⁺, Ni²⁺, and Zn²⁺were measured.

Dry matter yields were depressed due to salt toxicity, while DTPA‐extracted Cu²⁺correlated with plant uptake of Cu²⁺for both sludges. DTPA‐extracted Ni²⁺also correlated with plant Ni²⁺from the Ca(OH)₂‐sludge‐amended soil, although DTPA‐extracted Ni²⁺did not correlate with plant uptake of Ni²⁺from the FeCl₃‐sludge‐amended soil, DTPA‐extracted Zn did not correlate with plant uptake of Zn²⁺from any sludge‐amended soil. Soil‐solution composition correlated with plant uptake of Cu²⁺and Ni²⁺in both sludges; it also correlated with plant uptake of Zn²⁺from FeCl₃‐sludge‐amended soil but not from Ca(OH)₂‐sludge‐amended soil. DTPA extraction probably failed with Ni²⁺and Zn²⁺because of (i) its ineffectiveness at low pH, (ii) the inability of DTPA to buffer each soil extract near pH 7.3, and (iii) increased amounts of soluble chelated micronutrients at higher sludge rates and higher soil pHs. Soil‐solution composition seemed to fail only where micronutrient cations in solution probably were present largely as organic chelates     

Changes in CO<Subscript>2</Subscript>, <Superscript>13</Superscript>C abundance,inorganic nitrogen, β-glucosidase,and oxidative enzyme activities of soil during the decomposition of switchgrass root carbon as affected by inorganic nitrogen additions

This study was conducted to investigate the effect of inorganic nitrogen (N) and root carbon (C) addition on decomposition of organic matter (OM). Soil was incubated for 200 days with nine treatments (three levels of N (no addition (N0) = 0, low N (NL) = 0.021, high N (NH) = 0.083 mg N g⁻¹ soil) × three levels of C (no addition (C0) = 0, low C (CL) = 5, high C (CH) = 10 mg root g⁻¹ soil)). The carbon dioxide (CO₂) efflux rates, inorganic N concentration, pH, and potential activities of β-glucosidase and oxidative enzyme were measured during incubation. At the beginning and the end of incubation, the native soil organic carbon (SOC) and root-derived SOC were quantified by using a natural labeling technique based on the differences in δ ¹³C between C3 and C4 plants. Overall, the interaction between C and N was not significant. The decomposition of OM in the NH treatment decreased. This could be attributed to the formation of recalcitrant OM by N because the potentially mineralizable C pool was significantly lower in the NH treatment (3.1 mg C g⁻¹) than in the N0 treatment (3.6 mg C  g⁻¹). In root C addition treatments, the CO₂ efflux rate was generally in order of CH > CL > C0 over the incubation period. Despite no differences in the total SOC concentration among C treatments, the native SOC in the CH treatment (18.29 mg C g⁻¹) was significantly lower than that in the C0 treatment (19.16 mg C g⁻¹).     

Methane and nitrous oxide emissions as affected by organic–inorganic mixed fertilizer from a rice paddy in southeast China

Purpose

The effects of commercial compost fertilizer application on trace gas emissions are not well understood due to a lack of field experiments. The objective of this study was to evaluate the emissions of methane (CH₄) and nitrous oxide (N₂O) along with grain yield from a rice paddy as affected by different organic–inorganic mixed fertilizer (OIMF) treatments.

Materials and methods

A field experiment was initiated in 2006 with chemical compound fertilizer (CF) and three OIMF amendments including pig manure compost (PMC), Chinese medicine residue compost (CMC), and rapeseed cake compost (RCC), from a rice paddy in southeast China. The emissions of CH₄ and N₂O were simultaneously measured using the static opaque chamber method over the entire rice growing season in 2011. Soil biotic parameters were measured in soil collected after the rice was harvested in 2011.

Results and discussion

Relative to the control, the OIMF treatments significantly increased CH₄ emissions by 56–99 %, mainly due to exogenous organic substrate input, whereas no difference was observed in the CF treatment. The N₂O emissions were stimulated substantially by an average of 40 % due to nitrogen fertilization compared with the control. Consecutive OIMF application tended to increase the grain yield, making it marginally higher than that of the CF treatment (7 %, P?=?0.06). Compared with the control, the CF treatment slightly decreased the global warming potential and greenhouse gas (GHG) intensity, while they were remarkably increased in the OIMF treatments. Over the 5-year period of 2006–2011, the annual soil carbon sequestration rate was estimated to be 1.19 t C ha^?1 year^?1 for the control and 1.73–1.98 t C ha^?1 year^?1 for the fertilized treatments.

Conclusions

Our results suggest that despite the beneficial effects of increasing both grain yield and soil organic matter, OIMF application such as PMC, CMC, and RCC may be responsible for increased global warming due mainly to the stimulated CH₄ emissions. This effect should be thus taken into account when balancing agricultural production and GHG mitigation.     

Soil fungal distribution and functionality as affected by grazing and vegetation components of integrated crop–livestock agroecosystems

Integrated crop and livestock (ICL) agroecosystems are characterized by a mixture of perennial or annual vegetation grazed by livestock and annual harvested crops. Compared to annual crops, ICLs hold the potential to enhance soil organic matter (OM) inputs, carbon sequestration, nutrient cycling, and water conservation. Soil fungi play an essential role in the transformation of OM and nutrients and soil structure stabilization; however their specific role in OM transformations in ICL agroecosystems has not been studied. This study evaluated mycorrhizal and saprophytic fungal populations (via fatty acid methyl ester profiles; FAME) and saprophytic fungal functionality (via FungiLog analysis) under two ICL agroecosystems and a continuous cotton (Gossypium hirsutum L.) system in the Southern High Plains of the U.S. The first ICL system included non-irrigated perennial native grasses, an annual cotton and foxtail millet (Setaria italica) rotation and deficit-irrigated ‘WW-B. Dahl’ old world bluestem (Bothriochloa bladhii; OWB). The second ICL agroecosystem consisted of deficit-irrigated OWB and bermudagrass (Cynodon dactylon). The effect of grazing by cattle was evaluated via grazing exclusion areas. Abundance of saprophytic fungal FAMEs (10–26% of total FAMEs) and mycorrhizal FAMEs (2–24% of total FAMEs) were higher under ICLs compared to the continuous-cotton system at 0–5 cm. Overall, vegetation impacted the distribution of the fungal FAME markers, whereas the fungal saprophytic functionality was more sensitive to grazing. Perennial vegetation of ICLs was associated with an increase in fungal markers (saprophytic and mycorrhizal) as well as increased soil OM content. Greater utilization of multiple C sources and increased saprophytic fungal functional indices were found under cotton, non-grazed perennial vegetation (with exception of bermudagrass) and the rotation under millet. Among the grazed perennial vegetation, bermudagrass showed the highest fungal FAMEs abundance and functional diversity values. These fungal improvements were also reflected in the highest OM content under this grass, potentially indicating improved sustainability under the OWB and bermudagrass agroecosystem.