Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity.  The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization  in the wheat-maize cropping system.  Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure).  Crop yield and the properties of topsoil were measured yearly from 2001 to 2009.  C and N contents were measured at five different depths in 2001 and 2009.  The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments.  The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize.  Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions.  In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC.  All fractions were higher under the manure application treatments than under the inorganic fertilization treatments.  Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm).  This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments.  The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.

The current investigation aimed at evaluating the impact of as-is biochar (BC) and phosphorous (P)-loaded biochar (PBC) (3%) on the growth and biochemical characteristics of rice under exposure to vanadium (V) (60 mg L^-1).  The results indicate that rice plants exposed to V-only treatment experienced a decline in growth parameters.  Conversely, the inclusion of BC and PBC caused a noteworthy increase in physiological traits.  PBC performed well in stress environments, specifically, shoot and root fresh weight increased by 82.86 and 53.33%, respectively, when compared to V-only treatment.  Additionally, the SPAD chlorophyll of the shoot increased by 13.05% than V-amended plants.  Moreover, the antioxidant enzyme traits of plant shoot and root, such as superoxide dismutase (SOD by 56.11&117.35%), catalase (CAT by 34.19&35.77%), and peroxidase (POD 25.90&18.74%), exhibited significant increases when compared to V-only amended plants, respectively.  These findings strongly suggest that the application of BC and PBC can trigger biochemical pathways that facilitate biomass accumulation in meristematic cells.  However, further investigations are required to elucidate the underlying mechanisms responsible for this growth promotion.