Distribution Of Soil Nutrients Research Articles

Potential Roles of Soil Microorganisms in Regulating the Effect of Soil Nutrient Heterogeneity on Plant Performance

The spatially heterogeneous distribution of soil nutrients is ubiquitous in terrestrial ecosystems and has been shown to promote the performance of plant communities, influence species coexistence, and alter ecosystem nutrient dynamics. Plants interact with diverse soil microbial communities that lead to an interdependent relationship (e.g., symbioses), driving plant community productivity, belowground biodiversity, and soil functioning. However, the potential role of the soil microbial communities in regulating the effect of soil nutrient heterogeneity on plant growth has been little studied. Here, we highlight the ecological importance of soil nutrient heterogeneity and microorganisms and discuss plant nutrient acquisition mechanisms in heterogeneous soil. We also examine the evolutionary advantages of nutrient acquisition via the soil microorganisms in a heterogeneous environment. Lastly, we highlight a three-way interaction among the plants, soil nutrient heterogeneity, and soil microorganisms and propose areas for future research priorities. By clarifying the role of soil microorganisms in shaping the effect of soil nutrient heterogeneity on plant performance, the present study enhances the current understanding of ecosystem nutrient dynamics in the context of patchily distributed soil nutrients.

Effects of irrigation at flowering stage on soil nutrient and root distribution in wheat field

To provide theoretical support the full use of water and fertilizer resources for wheat, we explored the effects of irrigation on wheat yield, plant and soil nutrient distribution during flowering period and its relationship with root characteristics. We set up two treatments by using the 2 m deep soil column cultivation method with irrigation during flowering (T1) and no irrigation during flowering (T2), with the drought-resistant and high-yield cultivar Luomai 28 (LM28) and the high photosynthetic efficiency cultivar Bainong 207 (BN207) as materials. We measured contents of nitrogen, phosphorus and potassium in plants and soils, as well as the characteristics of soil roots. The results showed that ammonium, available phosphorus, and available potassium were mainly distributed in 0-80 cm soil layer, and that nitrate was mainly distributed in soil layer below 80 cm during wheat harvest. Irrigation at anthesis stage promoted wheat to absorb ammonium, available phosphorus and available potassium from the upper layer of soil and nitrate nitrogen from the lower layer but did not aggravate the deep leaching of nitrate. The root of wheat mainly concentrated in 0-60 cm soil layer and decreased with increasing soil depth. Dry matter accumulation, total nitrogen and total phosphorus were mainly distributed in wheat grains at maturity, while total potassium was mainly distributed in stems. Irrigation at anthesis stage significantly increased the 100-grain weight of wheat, and consequently the yield. Root morphology was negatively correlated with soil nitrate in 0-40 cm soil layer, positively correlated with soil ammonium in 80-100 cm soil layer and soil available phosphorus in 0-100 cm soil layer. Irrigation at anthesis stage promoted the full absorption of soil nutrients by roots at late filling stage, delayed the senescence of flag leaves after flowering, prolonged the functional period of transporting nutrients from vegetative organs to reproductive organs, leading nutrients in vegetative organs more fully transported to grains, increasing grain weight and yield.

Are active and former floodplain soils of the lower middle Elbe similar? A study of soil characteristics and possible implications for forest restoration

The analyses of soil properties and processes under the consideration of the spatial complexity of floodplains is a key step in the preparation of floodplain restoration measures. In that context, we analyzed how hydrogeomorphology influences soil physicochemical properties and formation processes in hardwood floodplain forests at the local scale. Our analyses are based on, 44 mixed topsoil samples, 135 soil drillings (2.0 m depth) and 18 reference pits (1.6 m depth) distributed in 44 hardwood floodplain forests along 150 km of the middle Elbe River. We considered four hydrogeomorphic units (HGUs) along a lateral floodplain gradient. Two HGUs located in the active floodplain and defined by their morphology Active High (AH), and Active Low (AL), and two located in the former floodplain: seepage water influenced (FS), and disconnected from the river hydrology (FD). Our results indicate that the HGUs in the active floodplain benefit from a stronger connection to the river hydrology. Higher pHCaCl2 values in the active HGUs as well as expected higher total P contents due to river deposition result in increased phosphorous availability. Physicochemical parameters as lower pHCaCl2 and predominance of iron mottling found in the FD indicate increased P sorption, therefore lower Psol availability. However, HGUs in the former floodplain, particularly those disconnected from the river hydrology, are characterized by higher total carbon and nitrogen content. These results improve our understanding of the soil physicochemical dynamics and their interactions in the different hydrogeomorphic units, and could allow the evaluation of floodplain restoration measures based on soil nutrient distribution to increase the potential of restored forests to develop on the selected geographic setting.

Regulation of Abiotic Factors on Aboveground Biomass and Biodiversity of Ditch Slope in Coastal Farmland

Ditch plant biomass and diversity play an important role in maintaining ditch ecosystem structure and function stability, which are subject to environmental changes. However, the regulation of abiotic factors on the aboveground biomass and diversity of plants on the slopes of coastal agricultural ditches remains unclear. In this study, the spatial distribution of soil physicochemical properties, aboveground biomass, and diversity of vegetation on different slope positions (upper slope, middle slope, and lower slope) and slope aspects (north-south direction) of farmland drainage ditches and their correlations were investigated through field surveys of vegetation on the slopes of coastal farmland drainage ditches at different sampling sites. First, water content and bulk density) decreased with the increase of slope position, while the salinity showed the opposite spatial distribution characteristics and the distribution of soil nutrients in space was mainly concentrated in the 0–20 cm soil layer. Second, the aboveground biomass of vegetation was significantly higher on the south slope than on the north slope, with the highest biomass at the lower slope on the south slope and higher aboveground biomass on the north slope at the upper and middle slopes. The Shannon-Wiener index, Pielou index, and Margalef index of ditch slope vegetation in Dongying and Binzhou farmland ditch slopes showed the same pattern of change at different slope positions and directions, which were significantly higher at the upper and middle slopes than at the lower slopes. In contrast, the Simpson index showed the opposite pattern, decreasing with the increase in slope position. Further, WC, BD, organic matter content, and total nitrogen content had positive effects on vegetation aboveground biomass, while soil pH, salinity, and available potassium content hindered vegetation growth. Finally, the Shannon-Wiener index and Pielou index were positively correlated with soil BD and available phosphorus content, and negatively correlated with organic matter and total nitrogen content, while the Simpson index was positively correlated with soil BD and WC, and had a significant negative correlation with soil salinity.

Spatiotemporal prediction and optimization of environmental suitability in citrus-producing areas

The increasing need for citrus has driven the rapid expansion of citrus planting areas. However, not all areas are suitable for growing citrus. It is necessary to understand the future changing trend of environmental suitability in citrus-producing areas. Here, based on the soil nutrient data of citrus cultivation from 2006 to 2018, the spatiotemporal kriging method was used to predict the spatiotemporal distribution of soil nutrients in Zigui County, Hubei Province. Then, geographical and meteorological conditions were combined to evaluate the suitability for citrus cultivation at temporal and spatial levels, and the results were verified by the yield and quality data of citrus. The results showed that from 2018 to 2027, the overall suitability of the citrus-producing area displayed a gradually rising trend, with the “suitable” producing area increasing from 4.5% to 20.16%. The validation results indicated that the mean relative errors of spatiotemporal predictors were less than 30% except for the effective iron. Correlation analysis revealed that the proportion of “moderately suitable” and “suitable” orchards had significant positive correlations with annual yield. The low suitability of Maoping town was mainly attributed to its soil acidification and available P content, and that of Shazhenxi town was ascribed to its low soil contents of available P and N. The optimal fertilization scheme was constructed by an artificial neural network to optimize the fertilization status of some citrus producing areas. This study has created a dynamic assessment of the environmental suitability of citrus production areas to support improvements in citrus production.

Drought Shapes Photosynthetic Production Traits and Water Use Traits along with Their Relationships with Leaves of Typical Desert Shrubs in Qaidam

Leaf functional traits in drylands are sensitive to environmental changes, which are closely related to plant growth strategies and resource utilization ability and can reflect the balance of substance synthesis and water loss. However, the influence of environmental factors on photosynthetic production traits and water use traits is still unclear in drylands. In this study, nine environmental factors (climatic characteristics and soil physical and chemical properties), leaf net photosynthetic rate (A), transpiration rate (E), and stomatal conductance (GSW) were measured via 60 plant samples and 45 soil samples, which were collected at five sampling sites according to rainfall gradient. Redundancy analysis (RDA), structural equation model (SEM), and regression analysis were used to analyze the influencing mechanism of drought on photosynthetic production traits and water use traits. The results provided the following conclusions: (i) The hydrothermal condition determined A, E, and GSW by affecting the spatial distribution of soil nutrients (SN) and soil salinity (SS); meanwhile, temperature was able to affect A, E, and GSW directly. (ii) The water content (WC) was the key driver of the strength of the synergistic relationship between photosynthetic production traits and water use traits; soil salinity (SS) was the main driver of the synergistic relationship between E and GSW.

Drivers of nutrient content and spatial variability of soil multifunctionality in the topsoil of Kyrgyzstan

Soil nutrient status is a crucial measure of soil fertility, which not only coordinates and provides the nutrients necessary for plant growth, but also stimulates the decomposition of soil humus and biogeochemical cycles. Therefore, understanding the distribution characteristics of soil nutrients in the Kyrgyzstan, while exploring the drivers of their variability, is important for understanding ecological processes and the distribution of soil resources. Simultaneously, the study of the spatial distribution of soil multifunctionality and its drivers across Kyrgyzstan can better elucidate the functions of the entire ecosystem, assist in optimizing the allocation of resources and serve as a reference material for the scientific and rational management of the country’s soil ecosystems. In this paper, We have used field sampling data from Kyrgyzstan, to examined the geographic variability and distribution of soil nutrients and soil multifunctionality within different soil depths, as well as the drivers in the country, using a combination of factor analysis and structural equation modeling (SEM). Findings indicated: (1)The topsoil of Kyrgyzstan (0–30 cm) stores 4.24 ± 0.59 Pg of SOC, 0.33 ± 0.06 Pg of total nitrogen (TN), 0.31 ± 0.03 Pg of total phosphorus (TP), and 5.12 ± 1.84 Pg of total potassium (TK). The nutrient reserves of various land-cover categories vary greatly across the nation, with grasslands accounting for the largest reserves (40%) but urban areas allocating the smallest proportion (0.3%). (2): the analysis revealed that using the linear or nonlinear fitting equations, the majority of soil nutrients exhibited a strong correlation with each other and also environmental parameters; (3): in Kyrgyzstan, soil multifunctionality varied substantially from –0.63 to 2.30 across regions. (4): according to the SEM results, NPP, wind speed (VS), MAP, longitude (Lon), SWC, and pH directly affected soil multifunctionality. In addition, several indirect effects of ST, MAT, Sard, and latitude (Lat) on soil multifunctionality were observed. Lon, map, SWC, and pH also had various direct and indirect impacts on soil multifunctionality. The findings of this study shed light on the functions of the entire soil ecosystem in the Kyrgyz Republic that help better predict the effects of environmental changes on ecosystem multifunctionality in drylands and provide a scientific basis for rational utilization of soil resources, efficient management of dryland soils, and prevention of land productivity decline in the country.

Impact of conservation tillage on the distribution of soil nutrients with depth

Conservation tillage, defined as no-till with/without straw stubble covering, reduced tillage, or minimum tillage in this study, is widely used to mitigate the negative effects of intensive tillage. Achieving sustainable agricultural development and eco-environmental protection requires a deeper understanding of the effect of conservation tillage on soil chemical properties (e.g., organic matter (OM), nutrient elements, metal cations, and pH); we investigated these properties in this study using a global meta-analysis based on the data collected from 203 studies published worldwide since 1983. The results showed that compared with conventional tillage without straw stubble covering (CT), conventional tillage with straw stubble covering (CTS), no-till with straw stubble covering (NTS), no-till without straw stubble covering (NT), reduced tillage without straw stubble covering (RT), and minimum tillage without straw stubble covering (MT) significantly increased the topsoil (0–15 cm) organic matter (OM), organic carbon (OC), total carbon (TC), total nutrients (N, P, and K), available nutrients (N, P, and K), calcium ions (Ca2+), magnesium ions (Mg2+), and cation exchange capacity (CEC), respectively. However, the effects of conservation tillage on sodium ion (Na+) and pH are insignificant or inconsistent. In particular, the existing research data could not conclude whether conservation tillage can significantly increase Na+, or if pH was affected by conservation tillage practices, and both significant increases and decreases were observed. This meta-analysis also suggested that CTS, NTS, and NT significantly (p < 0.05) increased the subsoil (15–40 cm) OC, total nutrients (N, P, K), AN, and AP, respectively, compared to CT. Finally, compared with NT, NTS significantly increased the topsoil OM, OC, TC, TN, TP, TK, AN, and AP by 14%, 5%, 37%, 8%, 8%, 3%, 11%, and 16%, respectively. These findings indicate that conservation tillage can effectively improve the soil chemical properties, and straw stubble covering can greatly enhance the content of OM, OC, nutrient elements, and other soil chemical properties.

Disentangling effects of upslope runoff and sediment on soil nutrients on the hilly slopes of the Loess Plateau, China

Upslope runoff and sediment critically influence soil erosion, while their impact on the subsequent downslope nutrient distribution has not been examined, consequently hindering the exact assessment of the effects of erosion on soil biogeochemical cycles. Herein we selected two groups of wide and narrow slopes on the middle Loess Plateau, with each slope group including slopes with and without upslope runoff and sediment. For each slope, we collected soil samples from topsoil along the slope at different distances from the upper slope to the lower slope, and collected samples from depths of 0–60 cm at the upper, middle and lower positions of the slope. The contents of soil organic matter and nutrients were analysed. The purpose of this study was to disentangle the effects of upslope runoff and sediment on spatial distribution of soil nutrients on slopes of different widths. We showed that compared with slopes without upslope runoff and sediment, upslope runoff and sediment increased the content of most nutrients in topsoil on the wide slope, but had a contrasting effect on the narrow slope. Upslope runoff and sediment reduced the random spatial heterogeneity of soil nutrients on both the wide and narrow slopes, with greater effects observed on the narrow slope. The influence of upslope runoff and sediment on the profile distribution of soil nutrients varied with slope position and slope width, and was nutrient type-dependent. These results indicated that slope topographical conditions interact with upslope runoff and sediment in influencing vertical and horizontal patterns of soil nutrients on slopes.

Can plants integrate information on above-ground competition in their directional responses below ground?

Light competition can induce varying above-ground responses in plants. However, very little is known regarding the effect of above-ground light competition cues on plant responses below ground. Here we asked whether light competition cues that indicate the occurrence and direction of neighbours above ground might affect directional root placemat. In a common-garden experiment, we examined the integrated responses of the annual procumbent plant Portulaca oleracea to light competition cues and soil nutrient distribution. Soil nutrients were distributed either uniformly or in patches, and light competition was simulated using a transparent green filter, which was spatially located either in the same or opposite direction of the soil nutrient patch. As predicted, root proliferation of P. oleracea increased in the direction of the enriched soil patches but was homogenously distributed under the uniform nutrient distribution. Interestingly, root distribution was also affected by the light competition cue and increased in its direction regardless of the location of the soil patches. Our results provide initial support to the idea that below-ground plant responses to competition might also be regulated by above-ground neighbour cues, highlighting the need to further investigate the combined effects of both above- and below-ground competition cues on root behaviour.

Continuous Cropping and Fertilization on Vertical Distribution of Major Nutrients, SOC Dynamics Through FT-IR Spectroscopy and Developing Soil Quality Indices Under Sandy Clay Loam Soil

ABSTRACT Continuous application of farm yard manure and mineral fertilizer significantly affects the soil available nutrient and distribution of nutrients in soil. Balanced application of mineral fertilization (100% NPK) along with FYM @10 t ha−1 has significantly changed the soil labile C and recalcitrant pool. The study shows that integrated nutrient management has recorded the highest transmittance intensity of hydrophilic bond of carboxyl (1698–1701 cm−1) (3500–3200 cm−1 & 1400 cm−1) and aromatic (1650 cm−1), benzenes and alkenes (2922–2926 cm−1), disulfide (500–400 cm−1), and phosphorus esters (800–580 cm−1) bonds. Soil organic carbon (SOC), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), labile and recalcitrant pools have observed higher in INM plots than super optimal (150% NPK), optimal (100% NPK), and with micronutrient (100% NPK +Zn). The addition of manure and mineral fertilizers has increased the SOC stocks and SOC sequestration. Soil quality indices were developed using principal component analysis and INM (T8) showed the highest soil quality index which has 10.2 (SQIA) and 10.6 (SQIW) percent higher response than super optimal dose (T3) and other optimal doses (T2, T4, T5 & T9) are on par which each other and lowest in control of intensive farming over four decades. The significant change in sustainable yield index (SYI) of finger millet and maize has observed in plot which received T8 followed by T3, and other optimal doses were least significant with each other and lowest in control plot.

Effects of different earthworm ecotypes on soil nutrients distribution under straw return management in a maize agroecosystem

AbstractEarthworms are among the most common soil macrofauna taxa in cropland areas in the Loess Plateau and exert a large influence on soil nutrient cycling. The impacts of earthworms are related to the way different earthworm ecotypes process the soil. However, there are relatively few studies on the differing impacts of earthworm ecotypes on soil nutrient dynamics. Here we carried out a field plot experiment to explore the characteristics of soil nutrients, microbial populations, and enzyme activity subjected to two ecological groups (epigeic and epi‐anecic) in a maize system under two typical straw return managements (straw mulching and incorporation). Epigeic (EP), epi‐anecic (EN), and the combined presence of epigeic and epi‐anecic earthworms (EM) increased soil nutrients, microbial populations, and enzyme activity and improved maize growth. Under the straw incorporation mode, the promotion effect of earthworm treatment shows: EM &gt; EN &gt; EP. Compared with CK, EM significantly increased the nutrient content of all soil layers, and the activities of invertase, urease, phosphatase, and catalase increased by 8.6%–38.5%, 5.8%–33.7%, 13.7%–32.4%, and 8.1%–36.2%, respectively. The abundance of soil bacteria, actinomycetes, and fungi increased by 21.8%–37.7%, 11.7%–43.6%, and 46.2%–58.1%, respectively. Under straw mulching conditions, EP significantly increased the nutrient content, enzyme activity, and microbial content in the 0–10‐cm soil layer. The results showed clear effects of the earthworm ecotype on soil fertility under different straw application methods. These findings are helpful for revealing the role of different earthworm ecotypes in the nutrient cycling processes of dryland farmland ecosystems.

Effects of Irrigation and Nitrogen Application on Soil Nutrients in Triploid Populus tomentosa Stands

Irrigation and nitrogen application directly affect the availability and distribution of soil nutrients. Understanding the response of soil nutrients to long-term water–fertilizer coupling conditions is helpful to improve the management and use efficiency. Irrigation was divided into three gradient levels, which accounted for 45%, 60%, and 75% (W1, W2, and W3) of the field water holding capacity. Based on pure nitrogen, four levels of nitrogen application were set: 0.0, 101.6, 203.2, and 304.8 kg·hm−2 (N0, N1, N2, and N3). We measured tree height and diameter at breast height (DBH), and we analyzed the chemical properties of the soil at 0–40 cm depth, from 2007 to 2020. The ranges of DBH, tree height, individual volume, and stand volume were 5.80–25.25 cm, 6.10–16.47 m, 0.01–0.37 m3, and 11.76–481.47 m3·hm−2, respectively. The contents of organic matter, total nitrogen, available phosphorus, and available potassium in the soil ranged from 8.60 g·kg−1 to 18.72 g·kg−1, from 0.21 g·kg−1 to 0.79 g·kg−1, from 8.09 mg·kg−1 to 47.05 mg·kg−1, and from 90 mg·kg−1 to 322 mg·kg−1, respectively. Soil pH value decreased rapidly at a rate of 0.31 units per year for the first five years. Irrigation and nitrogen application, and their interaction, had significant (p &lt; 0.01) effects on soil total nitrogen, available phosphorus, available potassium, and nitrate-nitrogen. We suggest maintaining the field water holding capacity above 60%, with a nitrogen application rate of 203.2 kg·hm−2, to save water, maintain soil fertility, and optimize soil nitrogen supply. Our study aimed to achieve scientific and accurate fertilization of Populus tomentosa stands over different periods, to alleviate the decline of soil fertility, and to improve the utilization rate of water and fertilizer through long-term nutrient monitoring.

Spatial distribution of soil nutrients and evaluation of cultivated land in Xuwen county.

It is of great significance to promote the quantitative research of soil science and the implementation of precision agriculture. On this basis, taking Xuwen County as the research object, this paper comprehensively analyzed the soil characteristics of cultivated land in Xuwen County and clarify the soil nutrient content and spatial distribution characteristics of cultivated land in Xuwen County, this paper comprehensively applied the methods of geostatistics, geographic information system (GIS) and fuzzy mathematics, and referred to the cultivated land quality grade standard (GB/T 33469-2016), to analyze the soil characteristics and evaluate the soil fertility of this region. The results show that the optimal interpolation model of soil pH and available phosphorus (AP) is a Gaussian model, and the optimal interpolation model of soil organic matter (SOM), available nitrogen (AN) and available potassium (AK) is a J-Bessel model. In addition, the spatial correlation of AK is weak, whereas pH, SOM, AN and AP show moderate spatial correlation. The proportion of excellent, good, average, medium and poor comprehensive fertility index are 26.00%, 32.67%, 19.33%, 19.00% and 3.00%, respectively. The overall level of soil fertility in Xuwen County is above the average, and the fertility quality presents an obvious trend of high in the South and low in the North. Areas that above average fertility are mainly distributed in Maichen Town, Qujie Town, Nanshan Town and Chengbei Town. The results can provide theoretical basis for improving the utilization rate of chemical fertilizer, fine management of cultivated land and ecological environment in this region, which can help in decision-making of precision fertilization.

PROPERTIES OF SOILS ALONG A TOPOSEQUENCE UNDERLAIN BY COARSE GRAINED GRANITE GNEISS IN IFE AREA SOUTH WEST NIGERIA

Research has shown that soil profiles are influenced by five separate, yet interacting factors: parent material, climate, topography, organisms and time which give soil profiles their distinctive character. Topography however, plays a major role in the variation of soil properties and nutrient distribution along a non-uniform agricultural landscape. This study was conducted to investigate the effects of topography on chemical properties of soil underlain by coarse grained granite gneiss at the teaching and research farm of Obafemi Awolowo University Ile Ife. Three profile pits was established at different physiographic positions along a toposequence (upper, middle and lower positions) were considered for this study. A total of eleven (11) samples were collected for routine laboratory analysis from the established horizons. The results revealed that the clay content increased with increase in profile depth while sand content decreases. Organic matter content was relatively low 0.2 – 1.35%, a result of continuous cultivation in the area. The values of available P (1.29 – 5.40ppm) showed that it is inadequate for crop production. The pH, exchangeable cations and exchangeable acidity values fluctuate across the pedons under investigation. The correlation between slope position and chemical properties showed that no singular property consistently showed the same level of significance on the entire slope.&#x0D; For effective management of the soils, organic inputs and usage of vegetal cover such as planting of cowpea and other crawling plants of economic importance should be adopted to assist in improving the organic matter content, conservation management practices should also be employed to prevent rapid soil degradation across the topography.

Effects of earthworm activities on soil nutrients and microbial diversity under different tillage measures

As a typical macrofauna in soil, earthworms alter soil structure through a series of activities, including feeding, digging, and excretion, thereby affecting farmland soil nutrients and microbial diversity. In this study, we evaluated the influence of earthworms on soil nutrient distribution and soil microbial diversity, under different tillage measures. Three cultivation methods [tillage (CT), no-tillage (NT), and no-tillage with straw (NTS)] were applied to the field. Five earthworm densities (0, 20, 50, 100, and 200 individuals/plot) were tested under each cultivation mode. Our findings showed that earthworm density improved organic C, N, and P contents in the tilled soil layer (0–30 cm). Contrastingly, in conventional tillage (CT) treatment, increases in earthworm density reduced the total N and P contents and increased the organic C content of the soil. Greater earthworm densities were associated with higher soil microbial abundances and diversities under NTS treatment, whereas the opposite effect was observed under CT treatment. Different earthworm densities also resulted in significant structural changes in the soil microbial community. Overall, these findings suggest that under the same farming method, earthworm density affects soil microorganism composition and diversity as well as soil environmental factors.

Effect of Long-Term Organic Amendment Application on the Vertical Distribution of Nutrients in a Vertisol

Soil nutrients in deep soils are important for nutrient cycling and plant growth. Organic amendments have been widely used for enhancing soil health and crop yield. However, little is known about the effects of organic amendments on the vertical distributions of soil nutrients. Based on a 32-year long-term organic amendment experiment, the objective of this study was to evaluate changes in the vertical distribution of nutrients in a soybean–wheat system Vertisol. The results showed that NPK with manure or straw application significantly increased soil organic carbon (SOC), total N, total P, alkali-hydrolyzable N, available P and available K above the 40 cm soil layer. Variations in soil micronutrients primarily occurred above the 20 cm soil layer, and the highest contents were observed for NPKWS and NPKPM, respectively. Nevertheless, large amounts of NO3−−N contents accumulated in the 120–200 cm depth with manure but not straw application, indicating a high potential risk of nitrate leaching in manure treatments. These findings suggested that the application of organic amendment (manure or straw) could be recommendable for improving soil nutrients along the soil profile. Straw incorporation could be used as an alternative option for sustainable agriculture in regions with inadequate manure resources or severe nitrate leaching.

Moldboard Plowing in Wheat–Fallow Systems of the Pacific Northwest: Effect on Yields, Organic Matter

A two‐year winter wheat–fallow system in the Pacific Northwest is practiced in areas with annual precipitation &lt;16 inches. Wheat is planted in the fall and harvested in the summer, followed by 13 to 14 months of fallow. The summer fallowing often involves different types of tillage practices to facilitate water storage and weed control, which can influence vertical distribution of soil acidity and nutrients in the profile, possibly affecting crop yields. Long‐term studies could help us understand soil nutrients and yield responses across different tillage and N rate applications. Earn 0.5 CEUs in Soil &amp; Water Management by reading the article and taking the quiz at https://web.sciencesocieties.org/Learning‐Center/Courses.

Nutrient foraging ability promotes intraspecific competitiveness in the clonal plant Hydrocotyle vulgaris

Many plant species forage for nutrients by accumulating more biomass or ramets where soil nutrient availability is high. Nutrient foraging ability differs between species and between genotypes within species, can increase plant performance when nutrients are patchy, and may lead to differences in competitive ability and have community-level effects. Effects of intraspecific variation in nutrient foraging ability could be particularly strong in clonal species, in which individual genotypes can form large clones and persist for long times. We tested the hypotheses that clones with greater foraging ability (1) have greater ability to compete with other clones of the same species but (2) experience greater competition within a clone. Sets of clonal fragments of five clones of the perennial, creeping herb Hydrocotyle vulgaris were grown alone, with a fragment of a different clone, or with a second fragment of the same clone in pots with a uniform or patchy distribution of soil nutrients. Consistent with the first hypothesis, foraging ability and between-clone competitiveness as measured by less negative competitive response were positively related when nutrients were patchy but not when they were uniform. Contrary to the second hypothesis, foraging and within-clone competitiveness were negatively related. Intraspecific competition both between and within clones could thus select for greater foraging ability. If this in turn increases ability to compete with other species, it may help explain the dominance of some clonal species.

Effect of Long-Term Fertilization on Aggregate Size Distribution and Nutrient Accumulation in Aeolian Sandy Soil.

Soil aggregates are the material basis of soil structure and important carriers of nutrients. Long-term application of organic and inorganic fertilizers can affect the composition of soil aggregates to varying degrees, which in turn affects the distribution and storage of soil nutrients. We report the results of a 15-year long-term field-based test of aeolian sandy soil and used the wet sieve method to analyze the stability of water-stable aggregates, as well as the distribution characteristics of nutrients in different particle size aggregates. Our results show that long-term application of organic fertilizer (M3) and combined organic–inorganic treatments (NPK1-M1, NPK1-M2, and NPK1-M3) help to increase the amount of organic carbon, inorganic carbon, and cation exchange in the macro-aggregates, and the improvement rates are 92–103%, 8–28%, and 74–85%, respectively. The organic content of the fertilizers also promotes the formation of macro-aggregates, and the stability of aggregates increase from 0.24 to 0.45. In contrast, the application of inorganic fertilizers (NPK1, NPK2, and NPK3) has no marked effect on the formation and stability of macro-aggregates; the application of inorganic fertilizers can merely maintain the organic carbon content of the soil. Correlation analysis shows that the application of organic fertilizers and chemical (inorganic) fertilizers containing phosphorus and potassium can markedly increase the content and reserves of available phosphorus and potassium across all aggregate sizes, and there is a significant positive correlation between these parameters and the amount of applied fertilizer (p < 0.05). Aggregates of various sizes in aeolian sandy soils in arid areas have the potential for greater nutrient storage. Therefore, organic fertilizers can be used in the agricultural production process to improve soil structure and fertility.