Soil organic matter (SOM) has a critical role in regulating soil phosphorus (P) dynamics and producing phytoavailable P. However, soil P dynamics are often explained mainly by the effects of soil pH, clay contents, and elemental compositions, such as calcium, iron, and aluminum. Therefore, a better understanding of the mechanisms of how SOM influences phytoavailable P in soils is required for establishing effective agricultural management for soil health and enhancement of soil fertility, especially P-use efficiency. In this review, the following abiotic and biotic mechanisms are discussed; (1) competitive sorption between SOM with P for positively charged adsorption sites of clays and metal oxides (abiotic reaction), (2) competitive complexations between SOM with P for cations (abiotic reaction), (3) competitive complexations between incorporation of P by binary complexations of SOM and bridging cations with the formation of stable P minerals (abiotic reaction), (4) enhanced activities of enzymes, which affects soil P dynamics (biotic reaction), (5) mineralization/immobilization of P during the decay of SOM (biotic reaction), and (6) solubilization of inorganic P mediated by organic acids released by microbes (biotic reaction). Graphical Abstract

Recently, biochar has been widely used for versatile applications in agriculture and environment sectors as an effective tool to minimise waste and to increase the efficiency of circular economy. In the present work, we review the current knowledge about biochar role in N, P and K cycles. Ammonia volatilisation and N₂O emission can be reduced by biochar addition. The content of available P can be improved by biochar through enhancement of solubilisation and reduction in P fixation on soil mineral, whilst high extractable K in biochar contributes to K cycle in soil. Liming effect and high CEC are important properties of biochars improving beneficial interactions with N, P and K soil cycle processes. The effectiveness of biochar on N, P and K cycles is associated with biochar properties which are mainly affected by feedstock type and pyrolysis condition.

Forms and availability of nitrogen (N) in biochars are influenced by both feedstock and pyrolysis temperature. We conducted an assessment to examine how feedstock composition and pyrolysis temperature impact crucial properties and nitrogen (N) content and distributions within biochars. We subjected feedstocks with 0.2% to 8.9% N to pyrolysis at 300 °C and 750 °C. Biochars derived from different feedstock types (n = 11) were assessed for pH, electrical conductivity (EC), total C, water-soluble C (WSC) content, yield, total and available N content, as well as for C and N retention. We examined the aromaticity of the biochars by analyzing the ratio of specific FTIR spectra bands. As the pyrolysis temperature increased, we observed a decrease in yield, total N content, and N in the forms of N-NH₄⁺ and N-NO₃⁻. Concurrently, with the intensification of the charring process, the WSC content experienced a sharp reduction. Most biochars experienced an increase in carbon (C) content along with a notable decrease in total nitrogen (N) content as the pyrolysis process intensified. As charring conditions intensified, available N forms, such as N-NH₄⁺ and N-NO₃⁻, were lost. Biochars obtained from pine bark, eucalyptus sawdust, sugarcane bagasse, and bamboo exhibited high C content, low N content, and C:N ratios exceeding 100:1. The losses of C and N were independent of each other, with N chemical species demonstrating higher volatility compared to C compounds. At a temperature of 300 °C, the extent of N loss during pyrolysis depended on the feedstock, and the N content in the resulting biochar could be predicted based on the N content in the original feedstock. Pyrolysis at 300 °C retained a substantial amount of N in biochars derived from chicken manure, castor oil cake, chitosan, and shrimp carcass. This preserved nitrogen can serve as a valuable nitrogen source for crop applications. Graphical Abstract

Alternaria species are well‐known aggressive pathogens that are widespread globally and warmer temperatures caused by climate change might increase their abundance more drastically. Early blight (EB) disease, caused mainly by Alternaria solani, and brown spot, caused by Alternaria alternata, are major concerns in potato, tomato and eggplant production. The development of EB is strongly linked to varieties, crop development stages, environmental factors, cultivation and field management. Several forecasting models for pesticide application to control EB were created in the last century and more recent scientific advances have included modern breeding technology to detect resistant genes and precision agriculture with hyperspectral sensors to pinpoint damage locations on plants. This paper presents an overview of the EB disease and provides an evaluation of recent scientific advances to control the disease. First of all, we describe the outline of this disease, encompassing biological cycles of the Alternaria genus, favorite climate and soil conditions as well as resistant plant species. Second, versatile management practices to minimize the effect of this pathogen at field level are discussed, covering their limitations and pitfalls. A better understanding of the underlying factors of this disease and the potential of novel research can contribute to implementing integrated pest management systems for an ecofriendly farming system. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The impact of climate change has become increasingly severe in drylands, resulting in heat stress and water deficiency and, consequently, reducing agricultural production. Biochar plays an important role in improving soil fertility. The properties of sandy soils where water deficiency occurs with a greater frequency need to be enhanced by biochar amendments to increase the water retention capacity (WRC). Few studies have reported the effects of biochar on the readily available water (RAW) of these soils or an evaluation of the optimal application rate of the biochar. In this study, we aimed to assess the effect of different biochar types and application rates on the soil properties related to water retention. Under laboratory conditions, we amended sandy soil with four different types of biochar (woodchip (WBC), waterweed of Ludwigia grandiflora (WWBC), poultry litter (PLBC) and bagasse (BBC)) at rates of 0%, 5%, 10%, 15%, 25%, 50%, 75% and 100%. Soils treated with zeolite and perlite, both conventional materials, were arranged for a comparative study. The water content in the amended soils was recorded at saturation, field capacity, wilting point and oven-dry. Our results show a reduction in the bulk density by increasing the amendment rate across all biochar types. Although the WRC increased with the application rate, the RAW reduced and peaked at a 5% (v/v) biochar content for almost all the biochar types. WBC and WWBC showed the highest RAW increments of 165% and 191%, respectively, at a 10% (v/v) rate. In most cases, higher rates (such as 75% (v/v) of PLBC) caused negative effects on the RAW. Following these results, it is clear that both the biochar type and the application rate significantly influence the hydrological properties and the RAW capacity of sandy soils. A 5% (v/v) biochar amendment could significantly improve the readily available water to mitigate drought in sandy agricultural soils.