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Abandonment of agricultural fields triggers the ecosystem recovery in the process referred to as secondary succession. The objective of this study was to find the impact of secondary succession during 12 years lasting abandonment of agricultural fields with loamy sand and sandy loam soils on soil properties, namely soil organic carbon content, pH, water and ethanol sorptivity, hydraulic conductivity, water drop penetration time (WDPT), and repellency index (RI). The method of space-for-time substitution was used so that the fields abandoned at different times were treated as a homogeneous chronosequence. The studied soils showed a permanent increase in WDPT and a monotonous decrease in pH and water sorptivity with the duration of field abandonment. The dependence of the other characteristics on the duration of field abandonment was not unambiguous. The ethanol sorptivity decreased between 0 and 8 years of field abandonment, and increased between 8 and 12 years, when it copied a similar course of sand content during abandonment. The hydraulic conductivity halved within the first eight years of field abandonment and then increased statistically insignificantly between 8 and 12 years of abandonment. The repellency index decreased statistically insignificantly between 0 and 8 years of abandonment and then increased between 8 and 12 years.

The possibility of using brown algae in agriculture as an alternative source of nutrients is currentlyunder study and discussion. Our study aimed to evaluate the effect of F. vesiculosus on the agrochemical properties of four soil types: Retisol loamy sand soil, Retisolloam, Retisol clay, and Histosol. The F. vesiculosus waste was added to soil samples at a rate of 0, 0.5, 1.0, 2.0, 5.0, and 10 wt%. The brown algaewaste application significantly decreased soil acidity in the substrates of all soil types, with the larger increasesfor Retisol loamy sand and Retisol clay than for Retisol loam and Histosol. The application of F. vesiculosus waste products increased the C content in all soil types except Histosol. The N and P content in soil substrates were not significantly affected by algaewaste application regardless of soil type. This study showed that the effect of F. vesiculosus waste application varies depending on the soil type, with the strongest impact on Retisol clay and the lowest on Histosol.

Background and aims Soil aggregation is a crucial aspect of ecosystem functioning in terrestrial ecosystems. Arbuscular mycorrhizal fungi (AMF) play a key role in soil aggregate formation and stabilization. Here we quantitatively analyzed the importance of experimental settings as well as biotic and abiotic factors for the effectiveness of AMF to stabilize soil macroaggregates. Methods We gathered 35 studies on AMF and soil aggregation and tested 13 predictor variables for their relevance with a boosted regression tree analysis and performed a meta-analysis, fitting individual random effects models for each variable. Results and conclusions The overall mean effect of inoculation with AMF on soil aggregation was positive and predictor variable means were all in the range of beneficial effects. Pot studies and studies with sterilized sandy soil, near neutral soil pH, a pot size smaller than 2.5 kg and a duration between 2.2 and 5 months were more likely to result in stronger effects of AMF on soil aggregation than experiments in the field, with non-sterilized or fine textured soil or an acidic pH. This is the first study to quantitatively show that the effect of AMF inoculation on soil aggregation is positive and context dependent. Our findings can help to improve the use of this important ecosystem process, e.g. for inoculum application in restoration sites.

Evaporation from the soil is an important component of evapotranspiration, and mulching greatly affects soil evaporation. We conducted numerical simulations to study the effect of the thickness of sand mulch on soil evaporation. We tested nine treatments: mulching with sand thicknesses of 1,3, 5, 6, 8, 10, 15 and 20 cm plus an unmulched control (CK). Accumulated evaporation was significantly lower, and the resistance to evaporation was significantly higher, for the mulched treatments than CK. The volumetric soil water content (SWC) was significantly higher for the mulched treatments than CK, but SWC varied little for thicknesses >5 cm. Heating was slower and more uniform for the mulched treatments than for CK. With the increase of the thickness of sand, the temperature transmission was slowed down. The change of soil temperature was not obvious at thicknesses >15 cm. A thickness of 5 cm was the most effective for storing water and preserving heat. Our results provide a theoretical basis and technical guidance for the effective use and management of soil water in farmland in arid regions.

The importance of PRE herbicide applications in cotton has increased since the evolution of glyphosate-resistant (GR) Palmer amaranth. Cotton producers are relying on residual herbicides for control of Palmer amaranth, as POST options are limited or ineffective. S-Metolachlor, acetochlor, fomesafen, and dicamba all provide PRE control of Palmer amaranth; however, little is known about the effect of irrigation rate on incorporation and herbicidal efficacy. In 2015, an experiment was conducted on fine sand and loamy sand soils to evaluate the influence of irrigation volume (0.0 to 12.7 mm ha−1) on Palmer amaranth control with PRE herbicides. Irrigation volume after herbicide application was significant for both S-metolachlor and acetochlor. Efficacy of S-metolachlor was greatest in plots receiving 6.4 and 12.7 mm of irrigation where Palmer amaranth biomass was reduced to 4 and 2% of a nontreated control (NTC), respectively, compared with 61% in plots with the 0-mm irrigation treatment. Palmer amaranth control by acetochlor incorporated at 3.2- to 12.7-mm irrigation did not differ but did reduce Palmer amaranth biomass compared with the 1.6-mm irrigation rate. Irrigation volume was not significant for the soil incorporation of fomesafen or dicamba. Across all herbicides, fomesafen-treated plots provided the most consistent control of Palmer amaranth, reducing its biomass to < 3% of NTC at all irrigation rates. Dicamba provided the least and most inconsistent control of Palmer amaranth, producing 17 to 51% of NTC biomass. Nomenclature: Acetochlor; dicamba; fomesafen; S-metolachlor; Palmer amaranth, Amaranthus palmeri S. Wats.; cotton, Gossypium hirsutum L. En algodón, la importancia de las aplicaciones de herbicidas PRE ha aumentado desde la evolución de Amaranthus palmeri resistente a glyphosate (GR). Los productores de algodón están dependiendo de herbicidas residuales para el control de A. palmeri, ya que las opciones POST son limitadas o inefectivas. S-metolachlor, acetochlor, fomesafen, y dicamba brindan control PRE de A. palmeri. Sin embargo, se conoce poco acerca del efecto de la dosis de riego sobre la incorporación en el suelo y la eficacia del herbicida. En 2015, se realizó un experimento en un suelo arenoso fino y en uno arenoso limoso para evaluar la influencia del volumen de riego (0.0 a 12.7 mm ha−1) sobre el control de A. palmeri con herbicidas PRE. El volumen de riego después de la aplicación del herbicida fue significativo para S-metolachlor y acetochlor. La eficacia de S-metolachlor fue mayor en parcelas que recibieron 6.4 y 12.7 mm de riego donde la biomasa de A. palmeri se redujo a 4 a 2% del testigo sin tratamiento (NTC), respectivamente, comparado con 61% en parcelas con 0 mm de riego. El control de A. palmeri con acetochlor incorporado con riego de 3.2 a 12.7 mm no difirió, pero redujo la biomasa al compararse con la dosis de riego de 1.6 mm. El volumen de riego no fue significativo para la incorporación en el suelo de fomesafen y dicamba. Entre todos los herbicidas, las parcelas tratadas con fomesafen brindaron el control más consistente de A. palmeri, reduciendo la biomasa a < 3% del NTC en todas las dosis de riego. Dicamba brindó el más inconsistente y el menor control A. palmeri, produciendo 17 a 51% de biomasa al compararse con el NTC.

We present a method to visually score 10 root architectural traits of the root crown of an adult maize plant in the field in a few minutes. Phenotypic profiling of three recombinant inbred line (RIL) populations of maize (Zea mays L.; B73xMo17, Oh43xW64a, Ny821xH99) was conducted in 2008 in a silt loam soil in Pennsylvania and in a sandy soil in Wisconsin, and again in 2009 in Pennsylvania. Numbers, angles and branching pattern of crown and brace roots were assessed visually at flowering. Depending on the soil type in which plants were grown, sample processing took from three (sand) to 8 min (silt-loam). Visual measurement of the root crown required 2 min per sample irrespective of the environment. Visual scoring of root crowns gave a reliable estimation of values for root architectural traits as indicated by high correlations between measured and visually scored trait values for numbers (r ² = 0.46-0.97), angles (r ² = 0.66-0.76), and branching (r ² = 0.54-0.88) of brace and crown roots. Based on the visual evaluation of root crown traits it was possible to discriminate between populations. RILs derived from the cross NY821 x H99 generally had the greatest number of roots, the highest branching density and the most shallow root angles, while inbred lines from the cross between OH43 x W64a generally had the steepest root angles. The ranking of genotypes remained the same across environments, emphasizing the suitability of the method to evaluate genotypes across environments. Scoring of brace roots was better correlated with the actual measurements compared to crown roots. The visual evaluation of root architecture will be a valuable tool in tailoring crop root systems to specific environments.

The application of pyrogenic carbon, biochar, to agricultural soils is currently discussed as a win-win strategy to sequester carbon in soil, thus improving soil fertility and mitigate global warming. Our aim was to investigate if biochar may improve plant eco-physiological responses under sufficient water supply as well as moderate drought stress. A fully randomized greenhouse study was conducted with the pseudo-cereal Chenopodium quinoa Willd, using three levels of biochar addition (0, 100 and 200 t ha-1) to a sandy soil and two water treatments (60% and 20% of the water holding capacity of the control), investigating growth, water use efficiency, eco-physiological parameters and greenhouse gas (GHG) fluxes. Biochar application increased growth, drought tolerance and leaf-N- and water-use efficiency of quinoa despite larger plant–leaf areas. The plants growing in biocharamended soil accumulated exactly the same amount of nitrogen in their larger leaf biomass than the control plants, causing significantly decreased leaf N-, prolineand chlorophyll-concentrations. In this regard, plant responses to biochar closely resembled those to elevated CO2. However, neither soil- nor plant–soil-respiration was higher in the larger plants, indicating less respiratory C losses per unit of biomass produced. Soil-N2O emissions were significantly reduced with biochar. The large application rate of 200 t ha-1 biochar did not improve plant growth compared to 100 t ha-1; hence an upper beneficial level exists. For quinoa grown in a sandy soil, biochar application might hence provide a win-win strategy for increased crop production, GHG emission mitigation and soil C sequestration.

Many agricultural soils worldwide in their natural state are deficient in phosphorus (P), and the production of healthy agricultural crops has required the regular addition of P fertilisers. In cropping systems, P accumulates almost predominantly in inorganic forms in soil, associated with aluminium, calcium and iron. In pasture soils, P accumulates in both inorganic and organic forms, but the chemical nature of much organic P is still unresolved. The P use efficiency (PUE) of fertilisers is generally low in the year of application, but residual effectiveness is important, highlighting the importance of soil P testing prior to fertiliser use. With increasing costs of P fertiliser, various technologies have been suggested to improve PUE, but few have provided solid field evidence for efficacy. Fluid fertilisers have been demonstrated under field conditions to increase PUE on highly calcareous soils. Slow release P products have been demonstrated to improve PUE in soils where leaching is important. Modification of soil chemistry around the fertiliser granule or fluid injection point also offers promise for increasing PUE, but is less well validated. Better placement of P, even into subsoils, also offers promise to increase PUE in both cropping and pasture systems.

This review highlights future needs for research on potassium (K) in agriculture. Current basic knowledge of K in soils and plant physiology and nutrition is discussed which is followed by sections dealing specifically with future needs for basic and applied research on K in soils, plants, crop nutrition and human and animal nutrition. The section on soils is devoted mainly to the concept of K availability. The current almost universal use of exchangeable K measurements obtained by chemical extraction of dried soil for making fertilizer recommendations is questioned in view of other dominant controlling factors which influence K acquisition from soils by plants. The need to take account of the living root which determines spatial K availability is emphasized. Modelling of K acquisition by field crops is discussed. The part played by K in most plant physiological processes is now well understood including the important role of K in retranslocation of photoassimilates needed for good crop quality. However, basic research is still needed to establish the role of K from molecular level to field management in plant stress situations in which K either acts alone or in combination with specific micronutrients. The emerging role of K in a number of biotic and abiotic stress situations is discussed including those of diseases and pests, frost, heat/drought, and salinity. Breeding crops which are highly efficient in uptake and internal use of K can be counterproductive because of the high demand for K needed to mitigate stress situations in farmers' fields. The same is true for the need of high K contents in human and animal diets where a high K/Na ratio is desirable. The application of these research findings to practical agriculture is of great importance. The very rapid progress which is being made in elucidating the role of K particularly in relation to stress signalling by use of modern molecular biological approaches is indicative of the need for more interaction between molecular biologists and agronomists for the benefit of agricultural practice. The huge existing body of scientific knowledge of practical value of K in soils and plants presents a major challenge to improving the dissemination of this information on a global scale for use of farmers. To meet this challenge closer cooperation between scientists, the agrochemical industry, extension services and farmers is essential.

Purpose Soil amendment with biochar can result in decreased bulk density and soil penetration resistance, and increased water-holding capacity. We hypothesized that adding biochar could moderate the reductions in infiltration rates (IR) that occur during high-intensity rainstorms in seal-prone soils, and hence result in reduced runoff and erosion rates. The objectives were to (i) evaluate biochar potential to improve infiltration and control soil erosion, and (ii) investigate the mechanisms by which biochar influences infiltration rate and soil loss. Materials and methods Rainfall simulation experiments were conducted on two physicochemically contrasting, agriculturally significant, erosion-prone soils of Israel that are candidates for biochar amendment: (i) non-calcareous loamy sand, and (ii) calcareous loam. Biochar produced from mixed wood sievings from wood chip production at a highest treatment temperature of 620 °C was used as the amendment at concentrations from 0 to 2 wt%. Results and discussion In the non-calcareous loamy sand, 2 % biochar was found to significantly increase final IR (FIR) by 1.7 times, and significantly reduce soil loss by 3.6 times, compared with the 0 % biochar control. These effects persisted throughout a second rainfall simulation, and were attributed to an increase in soil solution Ca and decrease in Na, and a subsequently decreased sodium adsorption ratio (SAR). In the calcareous loam, biochar addition had no significant effect on FIR but did reduce soil loss by 1.3 times. There were no biochar-related chemical changes in the soil solution of the calcareous loam, which corresponds to the lack of biochar impact on FIR. Surface roughness of the calcareous loam increased as a result of accumulation of coarse biochar particles, which is consistent with decreased soil loss. Conclusions These results confirm that biochar addition may be a tool for soil conservation in arid and semi-arid zone soils.