Biochar and microorganisms combined enhance crop growth and soil properties: Evidence from meta-analysis

Different soil amendments have varying effects on crop growth, yield and soil properties. The study evaluated the effect of poultry manure, inorganic fertilizer (NPK), and biochar-based fertilizer (organo-yield) on tomato growth, yield and post-cropping soil properties. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Data on tomato growth and yield were collected and soils were tested before and after the cropping seasons. Analysis of variance was performed on the data and the effect of soil amendments on tomato growth and yield was determined. The effect of soil amendments on post-production soil properties was tested by comparing soil properties before and after the cropping seasons with published critical values. Results showed that all amendments increased the growth and yield of tomato significantly (P 0.05) compared to the control (without soil amendments). Plant height was higher in plots applied with soil amendments as compared to the control, while stem girth was highest in poultry-manured plots. Poultry manure and organo-yield applied plants exhibited high tomato fruit number and yield compared to control plots. In terms of soil properties, poultry manure and organo-yield improved the soil’s physical and chemical properties. Organo-yield decreased the soil bulk density and increased the pH from 4.8 to 5.5, while, application of NPK only increased calcium content in the soil. The findings confirmed that soil amendments applied increased tomato growth, and yield and also improved soil bulky density and pH.

Decreased soil pH weakens the positive rhizosphere effect on denitrification capacity

Two-year field experimentation was carried out under a randomized block design replicated thrice consisting of fifteen treatments in total to investigate the influence of INM treatment combinations using FYM, vermicompost, biofertilizers like Azospirillum on crop growth, yield, nutrient uptake and soil properties. Careful observation from the growth indices confirmed that T8 recorded significantly the highest in terms of plant height (cm), number of tillers plant-1, CGR. Yield attributes were also confirmed to have found highest with treatment T8, respectively. Nutrient uptake both in grain and straw were also observed to have enhanced with T8 and organic source included treatments. Soil properties like pH, electrical conductivity, organic carbon, and available NPK were also found to have improved significantly with T8 over the course of investigation.

Evaporation and discharge from arable land with cropped or bare soils during winter. Measurements and simulations

After-effects of straw and straw-derived biochar application on crop growth, yield, and soil properties in wheat (Triticum aestivum L.) -maize (Zea mays L.) rotations: A four-year field experiment

Macro-and/or microplastics as an emerging threat effect crop growth and soil health

Effects of desertification on soil and crop growth properties in Horqin sandy cropland of Inner Mongolia, north China

We conducted a pot experiment using a wheat‐millet rotation to examine the effects of two successive rice‐straw biochar applications on crop growth and soil properties in acidic oxisols and alkaline cambosols from China. Biochar was incorporated into soil at rates of 0, 2.25 or 22.5 Mg/ha at the beginning of each crop season with identical applications of NPK fertilizer. In the oxisols, the largest biochar treatment enhanced soil pH and cation exchange capacity, decreased soil bulk density, improved soil P, K, Ca and Mg availability and enhanced their uptake, and increased wheat and millet yields by 157 and 150% for wheat grain and straw, respectively, and 72.6% for millet straw. In the cambosols, biochar treatment decreased soil bulk density, improved P and K availability, increased N, P and K uptake by crops and increased wheat and millet straw yields by 19.6 and 60.6%, respectively. Total soil organic carbon increased in response to successive biochar applications over the rotation. No difference in water‐soluble organic carbon was recorded between biochar‐treated and control soils. Converting straw to biochar and treating soils with successive applications may be a viable option for improving soil quality, sequestering carbon and utilizing straw resources in China.

Cyperus esculentus is highly adaptable to extremely arid conditions and functions of oil extraction and sand fixation. Numerous studies have investigated the influence of row spacing on traditional crop growth and soil physicochemical traits but have not determined how cultivation affects C. esculentus growth and soil properties. Therefore, we conducted a field experiment in a sandy land to explore the responses of the organ yields of C. esculentus, soil wind erosion, and soil properties to row spacing (30, 60, or 90 cm), and bare land was used as the control. The highest plant height, plant density, number of tillers, and organ yields were observed at 30 cm row spacing. However, the lowest degree of soil erosion was also observed at 30 cm row spacing, and the coverage of C. esculentus facilitated soil fixation and conservation. The levels of soil wind erosion in the control plot were 11.7, 3.1, and 4.9 times those at 30, 60, and 90 cm row spacing, respectively. The percentages of clay and silt increased, whereas sand particles decreased with decreasing levels of soil wind erosion. Soil texture improved, and soil nutrients and plant growth were altered. Soil nutrient concentrations, yields, and root nutrient concentrations were positively related to clay percentage and negatively related to sand particles. In addition, the microbial biomass carbon and nitrogen significantly increased in the C. esculentus treatment groups, suggesting that planting C. esculentus promotes the survival and development of microorganisms. Overall, this study indicated that planting C. esculentus can decrease the level of soil wind erosion and improve soil quality. Narrow row spacing (30 cm) has the highest crop yield and soil amelioration and produces optimal ecological and economic benefits.

Duplex soils constitute about 60% of the cropping region of Western Australia and are usually cropped with wheat or lupins. Extensive and deep root growth is particularly important to crop production on these soils, because the nutrient- and water-holding capacities of the A horizon are frequently low. However, properties of the soils and the Mediterranean-type climate impose several constraints to root growth. Physical and chemical properties of duplex soils are spatially variable, leading to pronounced variation (from metres to tens of metres) in the growth of roots and shoots. Both the A and B horizons often impede root growth mechanically, with bulk density and penetrometer resistance frequently exceeding 1.8 Mg/m3 and 2 MPa, respectively. Also, saturated conductivities of the B horizon are often <0.01 m/day, leading to waterlogging. Topsoil acidity is often a problem in lighttextured A horizons, with pH declining about 0.1 unit each decade in yellow duplex soils near Beverley, Western Australia, where pH is already usually <4.8. Conversely, in the B horizon of red-brown earths and, sometimes, yellow duplex soils, pH >7 restricts growth of roots of Lupinus angustifolius. Major constraints to root growth often occur together (e.g. waterlogging with acidity, salinity, or mechanical impedance), and this exacerbates problems of root growth and necessitates identification and amelioration of the particular combination of constraints to improve root growth. Although L. angustifolius is often grown on duplex soils, its roots are not suited to these soils. Rooting depth is restricted, and unlike wheat roots, those of L. angustifolius are poorly adapted to ramifying through the soil for efficient water and nutrient extraction. Lupinus angustifolius is also particularly sensitive to high pH, salinity, and, probably, waterlogging. Other species of lupin which are more tolerant of high pH (e.g. L. pilosus) and waterlogging (e.g. L. luteus) may be more appropriate on duplex soils.

Tillage systems need to be compared over an extended period of time to determine their transitional and long‐term impacts on crop growth and soil properties. A 15‐yr experiment established in 1976 compared reduced tillage systems with conventional fall moldboard plowing for production of continuous corn (Zea mays L.) on a Maryhill silt loam soil (Typic Hapludalf). Corn plant growth and yield and soil properties were compared for five tillage systems: fall plow (fall mold‐board plow + spring secondary tillage), fall chisel plow (fall chisel plow + spring secondary), spring plow, spring plow/secondary (spring plow + secondary), and no‐till. No‐till consistently resulted in slower plant growth than most or all of the other tillage systems. The fall plow and spring plow/secondary treatments resulted in grain yields averaging 5% more than fall chisel plow, 9% more than spring plow, and 16% more than no‐till yields. From 1976 to 1983, no‐till yields tended to increase relative to fall plow; from 1988 to 1990, however, no‐till yields were much less than fall plow. No‐till resulted in the lowest proportion of aggregates <5 mm in diameter, highest bulk density, and greatest penetrometer resistance. Penetrometer resistance of the spring plow plots increased at a slower rate with depth than the fall chisel plow system. Among soil properties measured, the proportion of aggregates <5 mm in diameter was most often significantly correlated with yield.

Residual effects of long-term land application of domestic wastewater

Crop residue management strategies have exhibited significant effects on crop growth and soil properties, which in turn may influence soil phosphorus (P) transformation and availability. In this study, the effect of long-term (83-year) crop residue management treatments (straw plus 45 or 90 kg N ha−1; straw burning in fall or spring; straw plus manure) on soil P availability and storage capacity in the surface (0–0.3 m) and subsurface (0.3–0.6 m) were investigated relative to straw incorporated into soil (control) in a wheat-fallow rotation in the Pacific Northwest. Compared to the control, N application significantly decreased soil available P by 37–49%, measured as Olsen-P, due to the higher P removal by the wheat crop. The significant decrease in NaOH-extractable inorganic P (Pi) by 31–42% and Oxalate-extractable Fe by 20–27% suggests N application induced Fe associated-Pi release to supply crop growth. Straw burning had no significant effect on soil P balance but decreased available P by 20–36%, which can be attributed to the transformation of labile Pi and/or moderately labile Pi to stable Pi and P downward transport due to the increased pH of 0.4–0.9 and the loss of organic carbon. Fall burning appeared to have a greater effect on soil properties and P chemistry than spring burning. Manure application significantly increased soil available P by 245% in surface soil in 2014 while resulted in obvious negative soil P storage capacity (− 103 mg P kg−1) and high potential of P downward transport due to long-term positive P surplus together with the increase in soil pH of 1.2.

Microbial inoculants derived from plant growth-promoting rhizobacteria (PGPR) offer eco-friendly alternatives to traditional chemical fertilizers, maintaining microbiota balance in agricultural systems. However, limited research has explored the combined effects of microbial inoculants and chemical fertilizers on crop growth and soil properties. In this study, we investigated seven fertilizer combinations, ranging from no fertilizer to various proportions of chemical fertilizers with microbial inoculants, on timothy (Phleum pratense L.) growth, chlorophyll content, soil properties, enzyme activities, and soil microbial communities. A randomized block design was employed to analyze these effects. The results indicate that the combination of 85% chemical fertilizer with microbial inoculants significantly increased timothy yield and chlorophyll content. In addition, a reduction to 55% chemical fertilizer in conjunction with microbial inoculants resulted in comparable yield to that of 100% fertilizer with no inoculants. The microbial inoculants treatments notably elevated soil catalase, urease, acid phosphatase, and invertase activities, along with soil fast-acting nutrient content. The sequencing results show that the abundance of beneficial bacteria increased, while that of fungi decreased in the soil rhizosphere after the application of microbial inoculants. This study underscored the potential of microbial inoculants combined with reductions in chemical fertilizers to enhance soil microbiology, nutrient content, and beneficial microbial abundance while suppressing pathogenic fungi, thereby promoting timothy growth and yield. These findings provide a theoretical basis for the use of microbial inoculants in sustainable agricultural practices, providing valuable insights for optimizing microbial inoculants and chemical fertilizer formulations to mitigate the sustainability challenges posed by conventional fertilizers.

With growing competition for water in different sectors, utilization of effluent water in agriculture is imperative. Paper mill effluent could be used in this sector as the effluents were found to be neutral, low saline and contained Na, Ca, Mg, Fe, F-, B, Cl $^-$ , SO $_4$ $^{2-}$ , NO $_3$ $^-$ , CO $_3$ $^{2-}$ and HCO $_3$ $^-$ ions at low to moderate concentrations. Irrigation by Emami paper mill effluent at different dilutions with fresh water had improved crops' yield attributes. No adverse impact on crop nutrients' uptake or soil properties was noticed. These depict that >60 to ⩽80% dilutions of (Emami) paper mill effluent with fresh water is optimal for proper growth of blackgram and maize, >20% for greengram and ⩽60% for rice and sunflower grown on acidic laterite soil in pots. Thus the study reveals that paper mill effluent holds promise for use in irrigation if diluted to levels within the acceptable limit of crops.