Unamended Plots Research Articles

Long-term restoration with organic amendments is clearer evidenced by soil organic matter composition than by changes in microbial taxonomy and functionality

Here, a degraded soil, located in a semi-arid Mediterranean region, was characterized 17 years after organic amendment with sludge or compost (differing in their stabilization degree) for restoration purposes. To do this, (i) soil physicochemical properties and plant cover, (ii) soil organic matter (SOM) content and composition, (iii) soil basal respiration and enzymatic activities, and (iv) abundance, taxonomic composition, and functionality (shotgun metagenomics) of microbial communities were studied. Increased SOM and nutrient contents were found in soil from amended plots with respect to the control, with no differences between amendment types. This is explained by the lasting effects of organic amendments and the higher plant cover. Thermal and pyrolytic analyses showed that the restoration process enriched soil mainly with SOM of intermediate recalcitrance and of high chemical diversity. SOM composition did not differ between amendment types. Increased microbial abundances and activities were found in the amended plots, without differences between compost and sludge. Shotgun metagenomics showed that microbial communities changed in taxonomic and functional terms between amended and unamended plots, but these differences were rather limited. The taxonomic differences between treatments were mainly driven by increasing abundances of Actinobacteria and decreasing abundances of Proteobacteria in soil from amended plots. Soil microbial communities in amended plots showed some functional adaptation to the increased nutrient contents and predominant nutrients forms. This, together with the higher microbial abundances detected, explained the conspicuous soil enzymatic activities reported in amended plots. The effectiveness of the studied soil restoration process was confirmed here from an integrative perspective.

Growth and Yield Response of Maize (Zea mays L.) to Integrated Nutrient Management of Biochar, Organic and Inorganic Fertilizers

Aims: Maize yield is largely influenced by integrated nutrient management of biochar, organic and inorganic fertilizers application. In view of this, field study to evaluate varying rates of chicken manure (CM), Gliricidia sepium biochar (GB) and NPK fertiliser on growth and yield of maize was carried out.
 Study Design: The study design was a 2 x 6 factorial arranged in Randomized Complete Block Design with three replications.
 Place and Duration of Study: The field study was carried out at Mampong- Ashanti in the Forest-Savannah transition zone of Ghana over 2 years in 2021 minor and 2022 major cropping seasons.
 Methodology: The study treatments were different rates of amendments using biochar, chicken manure and NPK (15-15-15) fertiliser; [10 t ha-1 CM, 300 kg ha-1 NPK, 2.5 t ha-1 GB, 150 kg ha-1 NPK + 1.25 t ha-1 GB, 1.25 t ha-1 GB + 5 t ha-1 CM and No fertiliser (Control)] which were applied to two maize varieties (Omankwa and Obatanpa). Physiological growth parameters (crop growth rate and relative growth rate) were determined. Vegetative growth parameter (leaf count) as well as yield and yield traits (number of lodged plants per plot, husked cob weight per plot, number of filled and unfilled cobs per plot and grain yield) were estimated.
 Results: The results revealed that the application of 10 t ha-1 chicken manure and 1.25 t ha-1 GB + 5 t ha-1 CM to Omankwa and Obatanpa maize outperformed in crop growth rate (RGR), relative growth rate (RGR) and leaf count compared to the unamended plots in both seasons. Omankwa had significantly higher filled cobs per plot than Obatanpa across seasons. The interaction of Omankwa and 10 t ha-1 CM and 1.25 t ha-1 GB + 5 t ha-1 CM gave higher number of filled cobs per plot than Obatanpa on same although not significantly different in both cropping seasons. The grain yield of maize was enhanced by soil amendments in the major and minor cropping seasons, especially with interaction of Obatanpa and 10 t ha-1 CM (7474.0 kg ha-1), (3473.4 kg ha-1) respectively. Obatanpa x 1.25 t ha-1 GB + 5 t ha-1 CM (6802.1 kg ha-1) interaction followed closely in grain yield in the major season.
 Conclusion: Both biochar, organic and inorganic fertilizers have varying effects on growth and yield of different maize varieties. For optimize maize grain yield, 10 t ha-1 CM or 1.25 t ha-1 GB + 5 t ha-1 CM application is recommended.

Study of the influence of the contribution of fragmented rameal wood and manure on the density of microscopic fungi and the density of mites and collemboles of a sandy loam soil in Constantine (Algeria)

The objective of our work is to study the influence of the contribution of Fragmented Rameal Wood (BRF) and cattle manure on the density of microscopic fungi and the density of mites and springtails of a limono-sandy soil in Constantine (Algeria). A 100 m² parcel is subdivided into 15 plots of 2 m² each with 5 different plots where we determined the species of microscopic fungi and their density during March, April, May, June and November 2014. Thus, the density of springtails and mites was monitored monthly from March 2014 to January 2015. The results obtained show that the contribution of BRF or BRF mixture to cattle manure have a beneficial effect on the evolution of the density of microscopic fungi and the density of springtails and mites in the amended plots compared to the unamended plots.

The effects of biochar on soil organic matter pools are not influenced by climate change

The sustainability of Mediterranean croplands is threatened by climate warming and rainfall reduction. The use of biochar as an amendment represents a tool to store organic carbon (C) in soil. The vulnerability of soil organic C (SOC) to the joint effects of climate change and biochar application needs to be better understood by investigating its main pools. Here, we evaluated the effects of partial rain exclusion (∼30%) and temperature increase (∼2 °C), combined with biochar amendment, on the distribution of soil organic matter (SOM) into particulate organic matter (POM) and the mineral-associated organic matter (MAOM). A set of indices suggested an increase in thermal stability in response to biochar addition in both POM and MAOM fractions. The MAOM fraction, compared to the POM, was particularly enriched in labile substances. Data from micro-Raman spectroscopy suggested that the POM fraction contained biochar particles with a more ordered structure, whereas the structural order decreased in the MAOM fraction, especially after climate manipulation. Crystalline Fe oxides (hematite) and a mix of ferrihydrite and hematite were detected in the POM and in the MAOM fraction, respectively, of the unamended plots under climate manipulation, but not under ambient conditions. Conversely, in the amended soil, climate manipulation did not induce changes in Fe speciation. Our work underlines the importance of discretely taking into account responses of both MAOM and POM to better understand the mechanistic drivers of SOC storage and dynamics.

The effect of bio-humus on Cardinal grape yield (Vitis vinifera L.) and nutrient contents of dark brown soil using drip irrigation systems under the open field conditions

The aim of this study was to investigate impact of bio-humus on Cardinal grape yield (Vitis vinifera L.) and nutrient contents of dark brown soil using drip irrigation systems under the open field conditions in the vineyard region of Azerbaijan. A field experiment was conducted in a Cardinal Vineyard farm located in Shamakhi district, Azerbaijan between May and October 2021. An experiment with one dose of bio-humus treatment (5 t.ha-1) and three replications, with a plot size of 1 ha treatment was used. There were performed drip irrigation, starting from May 15 up to September 15, every 15 days. The soil sampling and measurements carried out after harvest the application of bio-humus in soil and the soil samples were collected from depth of 20 cm. The results showed that addition of bio-humus increased fresh berryweight yield, contents of organic matter, total N, available P, and available micronurtient (Fe, Cu, Zn and Mn) in soil compared with control plots. The soils treated with bio-humus had significantly more EC in comparison to unamended plots. The addition of bio-humus in soil resulted in increase of soil pH.

Effects of Substrates and Buckling on the Rejection Capacity of Plantain (Musa sapientum L.) under the Eco-climatic Conditions of Gbado-Lite, Democratic Republic of the Congo

Compost and flambéing on the plantain (Musa sp. cv. AAB, var Ngbangele) offshoot power studied under the conditions of Gbadolite in the Democratic Republic of Congo, remain among the techniques that protect the soil and increase production in the face of factors limiting such as climate change and soil destroyer including NPK. The experimental device chosen was that of complete randomized blocks comprising 3 repetitions and 4 plots 3 m long. The plots were arranged so that the flamed cultivars were adjacent depending on the substrates including T0: control substrate or unamended plot; T1: substrate from sawdust; T2: substrate from rice husk; T3: substrate from slush. Each plot contained 10 sample suckers of plantains. The greenhouse was installed after applying the buckling technique. It was observed that a bulb produced an average of 4 weaned suckers in the control bulbs; 8 suckers weaned on bulbs installed on substrates originating from slush; 9 suckers weaned on bulbs planted on substrates made from sawdust and rice husk. The releases installed on the control plot experienced a post-buckling recovery rate of 66.7%; those planted on sawdust and rice husk gave 83.3% and the subjects planted on the substrate from slush experienced a recovery rate of 80%; these results showed that the flame suckers adapted to the greenhouse conditions. In view of these results, it should be noted that this technique remains a major asset for the production of healthy suckers and in large quantities.

Subsurface Manure Injection Reduces Surface Transport of Antibiotic Resistance Genes but May Create Antibiotic Resistance Hotspots in Soils.

Compared to surface application, manure subsurface injection reduces surface runoff of nutrients, antibiotic resistant microorganisms, and emerging contaminants. Less is known regarding the impact of both manure application methods on surface transport of antibiotic resistance genes (ARGs) in manure-amended fields. We applied liquid dairy manure to field plots by surface application and subsurface injection and simulated rainfall on the first or seventh day following application. The ARG richness, relative abundance (normalized to 16s rRNA), and ARG profiles in soil and surface runoff were monitored using shotgun metagenomic sequencing. Within 1 day of manure application, compared to unamended soils, soils treated with manure had 32.5-70.5% greater ARG richness and higher relative abundances of sulfonamide (6.5-129%) and tetracycline (752-3766%) resistance genes (p ≤ 0.05). On day 7, soil ARG profiles in the surface-applied plots were similar to, whereas subsurface injection profiles were different from, that of the unamended soils. Forty-six days after manure application, the soil ARG profiles in manure injection slits were 37% more diverse than that of the unamended plots. The abundance of manure-associated ARGs were lower in surface runoff from manure subsurface injected plots and carried a lower resistome risk score in comparison to surface-applied plots. This study demonstrated, for the first time, that although manure subsurface injection reduces ARGs in the runoff, it can create potential long-term hotspots for elevated ARGs within injection slits.

Water use - yield relationship of maize as influenced by biochar and inorganic fertilizer applications in a tropical sandy clay loam soil

Empirical relationship between maize yield and evapotranspiration as influenced by biochar and inorganic fertilizer has been scarcely investigated. Therefore, the study's objectives are to; (i) determine the yield response factor (Ky) of maize under drip irrigation with/without biochar and inorganic fertilizer application; (ii) determine if soil hydrophysical and chemical properties affect the response of maize to water stress under biochar and inorganic fertilizer applications, and (iii) determine the possible mechanism by which biochar improves yield and water use efficiency of maize under deficit irrigation. Field experiments were carried out using a factorial design. Two rates of biochar application (0 and 20 t/ha), two levels of fertilizer (0 and 300 kg/ha) were adopted under three water management strategies (100 % of Full Irrigation Treatment; FIT, 80 % FIT, and 60 % FIT) using drip irrigation. The crop evapotranspiration was determined using the soil water budget method while the grain yields were measured at harvest. Soil samples were collected at harvest and analyzed for chemical and physical properties. The relationship between maize yield, soil properties and Ky were determined using correlation analysis. Results from the study showed that the sensitivity of maize crops to water stress was greater than one 1 but reduced in soil treated with biochar compared to those without biochar. Ky under the unamended plot was 1.64 and reduced to 1.52 when applied with biochar. Ky was 1.45 in soil amended with only inorganic fertilizer and reduced to 1.27 when co-applied with biochar. Biochar decreased water depletion by maize, with the highest reduction in soil water depletion occurring in treatments that received the least water. A significant (P < 0.05) correlation between Ky and the soil properties showed that the soil chemical (Nitrogen, Phosphorus and Potassium) properties are primarily responsible for the reduced sensitivity of maize yield to water stress.

Response of soil chemical properties, enzyme activities and microbial communities to biochar application and climate change in a Mediterranean agroecosystem

Changing climatic conditions (warming and decreasing precipitation) have been found to be a threat to the agricultural sustainability of Mediterranean croplands. From the climate change perspective, biochar amendment may interact with the effects of warming and drought stresses on soil ecosystems. However, the responses of soil microbial communities to the joint effects of climate change and biochar in Mediterranean croplands are not sufficiently known. To help fill this knowledge gap, in this work we used a field experiment to determine the effects of partial rain exclusion alone or combined with a soil temperature increase in biochar-amended (20 t ha−1) and unamended plots under crop rotation on soil chemical properties, enzyme activities, and the microbial community activity, structure, composition, abundance, and functions. The biomass, composition, and activity of the soil bacterial and fungal communities were more responsive to biochar addition than to climate manipulation. Thus, soil chemical parameters, enzyme activities and the relative abundances of bacterial populations were not responsive to the interaction of biochar and climate manipulation, while the predicted functionality of the bacterial community was modified by both factors. Soil β-glucosidase activity significantly decreased in response to biochar addition and climate manipulation, while urease activity was significantly increased by biochar, and protease activity was significantly decreased by climate manipulation. Gram negative and fungal biomasses were significantly affected by the interaction of biochar with climate manipulation. Climate manipulation produced changes in the composition of the soil fungal community without loss of diversity. This study illustrates how the interactions between biochar amendment and future climate change scenarios influence microbially-driven ecosystem services related to the maintenance of nutrient cycles and biodiversity in a Mediterranean agroecosystem.

Rice straw biochar application to soil irrigated with saline water in a cotton-wheat system improves crop performance and soil functionality in north-west India

Applications of biochar to degraded soils have attracted considerable interest because of its capacity to enhance nutrients availability to the plants, sequester C and immobilize organic and inorganic pollutants. A five-year field experiment was conducted in a cotton-wheat system to investigate the effect of different levels of irrigation water salinity (0.3, 5, 10, and 15 dS m−1) and rice straw biochar (0, 2, 4, and 8 t ha−1) on the crop yield and soil functions. Rice straw-derived biochar was applied every year to cotton and its residual effect was observed on wheat. Results of the study indicated that regular irrigation with saline water (5–15 dS m−1) reduced both seed cotton (12–44%) and wheat grain (7–27%) yield. However, application of biochar (2–8 t ha−1) to plots irrigated with saline water showed 6–23% and 13–27% greater seed cotton and wheat grain yield compared with unamended plots, respectively. Likewise, biochar application to soil irrigated with canal or saline water showed significant beneficial effects on soil pH, EC, nutrient metabolism and availability, bulk density, infiltration rate and microbial biomass carbon. Our results indicated that biochar amendment especially at the optimum rate of 4 t ha−1 effectively promoted crop performance by ameliorating soil physical, chemical, and biological properties. In the absence of any chemical amendment for alleviating salinity stress, the results of the present study established that the biochar holds promising potential as a soil amendment in ameliorating soil functions and promoting plant productivity under saline water irrigated conditions.

The influence of soil amendments on a native wildflower seed mix in surface mine restoration

With a multitude of physical, biological, and chemical soil characteristics disrupted or degraded during surface mining, it is challenging to achieve proper reclamation, much less restoration, post‐mining. We sought to assess the potential of a native wildflower seed mix (NWSM) to establish and achieve high vegetative coverage in the first season using soil amendments. We also evaluated the influence of amendments on community composition and soil quality. In May 2018, we seeded a NWSM on a surface mine in experimental plots treated with either inorganic fertilizer, spent mushroom compost, or left untreated. Plant coverage and community composition within experimental plots were assessed in October 2018. Soil samples were collected at the beginning and end of the season to identify potential changes in organic carbon, nitrogen availability, bulk density, and pH. First‐season vegetation results indicate that soil amendments may not be ecologically necessary or economically sensible for initial revegetation using a NWSM. Unamended plots surpassed compost‐amended plots and equaled or surpassed fertilizer‐amended plots in coverage, species richness, and proportion of seedlings present that originated from the mix. However, results from soil analyses suggest that compost may be beneficial to meeting surface mine restoration goals by improving important soil characteristics, such as percent organic matter, labile carbon, nitrate content, and pH, that could aid ecosystem recovery. Given the high degree of heterogeneity both within and between surface mines, future work should focus on identifying initial soil characteristics that could enable land managers to meet both reclamation and restoration goals using a NWSM.

Bioavailability and health risk assessment of potentially toxic elements in popcorn kernel from sandy loam Ferric Luvisol amended with municipal solid waste compost

Application of municipal solid waste compost (MSWC) to marginal soil enhances crop growth but could also serve as source of pollutants into agroecosystem. There is scanty report on bioavailability of potentially toxic element (PTE) and the health risk of consuming popcorn kernel harvested from field fertilized with MSWC. Field trial was carried out in 2017–2019 to evaluate bioavailability of PTEs in kernel of popcorn harvested from field fertilized with MSWC. The trial was conducted at the experimental field of North-West University, Mafikeng campus South Africa. The treatments comprised three rates of MSWC including 0 t/ha (unamended, control), 4 t/ha and 8 t/ha arranged in randomized complete block design and replicated four times. One seed of popcorn was sown at 20 × 70 cm spacing per hole of 3 cm depth in a 6 × 4.2 m plot size. Growth and yield data were collected at maturity. Ears were harvested at maturity and the kernels were dried to 12% moisture content. Air-dried kernels (50 g) samples were collected and analyzed for essential mineral nutrient and some heavy metal(loid)s using ICP-MS. Measured concentrations of these heavy metal(loid)s were then used to calculate the health risk for adults and children. The results showed that uptake concentration was in the order K+ > HPO42− > Mg+2 > Ca2+ > Fe2+ > Cr6+ > Zn2+ > Mn2+ > Cu2+(mg/kg). Uptake concentration of metalloids: Al and Pd was significantly higher in the unamended. Bioavailability of PTE was highest in unamended plots. The average daily intake of the PTEs was within the recommended permissible level. The risk index value for oral pathway was < 1 for both adult and children population. Amending Ferric Luvisol with 80 t/ha MSWC enhanced popcorn growth and, concentration of accumulated PTEs in kernels at this rate, cannot pose health risk to both adult and children population.

Influence of compost and biochar on soil biological properties under turfgrass supplied deficit irrigation

Turfgrass landscapes are commonly maintained using deficit irrigation. Here we follow-up a prior study, which surveyed turfgrass establishment in plots amended with biochar or compost or a mixture of both and unamended control plots. Following establishment, the plots were differentially irrigated at either full (85% ETo replaced) or deficit (50% ETo replaced) levels for four years and sampled for analysis. Relationships between soil chemical parameters and microbial community biomass and profiles based on phospholipid fatty acid analysis and high throughput sequencing of bacterial/archaeal 16S rRNA genes were determined. Compared to the unamended control soils, compost amended soils with or without biochar underwent greater shifts in soil physiochemical and biological properties than those receiving biochar. Although the impact of compost on the microbial community lessened with time, even 5 years after its incorporation, compost amended soils had increased microbial biomass by 127% and 157% in full and deficit irrigated plots compared to unamended plots. Bacterial/archaeal communities compositionally were more divergent in response to deficit irrigation in the unamended soils than in those amended with compost or biochar. Both soil amendments resulted in reduced relative abundances of nitrifying bacteria and archaea. In compost-amended soils many taxa associated with plant growth promotion and carbon cycling increased in relative abundance, whereas no such effect was observed with biochar. Altogether, these results provide mechanistic insights into how organic amendments affect turfgrass systems and their associated soil microbial communities under full and deficit irrigation regimens.

Positive long-term impacts of restoration on soils in an experimental urban forest.

As urbanization increases worldwide, investments in nature-based solutions that aim to mitigate urban stressors and counter the impacts of global climate change are also on the rise. Tree planting on degraded urban lands-or afforestation-is one form of nature-based solution that has been increasingly implemented in cities around the world. The benefits of afforestation are, however, contingent on the capacity of soils to support the growth of planted trees, which poses a challenge in some urban settings where unfavorable soil conditions limit tree performance. Soil-focused site treatments could help urban areas overcome impediments to afforestation, yet few studies have examined the long-term (>5yr) effects of site treatments on soils and other management objectives. We analyzed the impacts of compost amendments, interplanting with shrubs, and tree species composition (six species vs. two species) on soil conditions and associated tree growth in 54 experimental afforestation plots in New York City, USA. We compared baseline soil conditions to conditions after 6 yr and examined changes in the treatment effects from 1 to 6 yr. Site treatments and tree planting increased soil microbial biomass, water holding capacity, and total carbon and nitrogen, and reduced soil pH and bulk density relative to baseline conditions. These changes were most pronounced in compost-amended plots, and the effects of the shrub and species composition treatments were minimal. In fact, compost was key to sustaining long-term changes in soil carbon stocks, which increased by 17% in compost-amended plots but declined in unamended plots. Plots amended with compost also had 59% more nitrogen than unamended plots, which was associated with a 20% increase in the basal area of planted trees. Improvements in soil conditions after 6 yr departed from the initial trends observed after 1 yr, highlighting the importance of longer-term studies to quantify restoration success. Altogether, our results show that site treatments and tree planting can have long-lasting impacts on soil conditions and that these changes can support multiple urban land management objectives.

Soil nutrient and nematode community changes in response to hardwood charcoal application

ABSTRACT A one-time, large application of biochar (charcoal) could increase soil carbon (C) content and improve overall soil quality. It is known that nematodes have effects on soil organic matter and nutrient cycling and are plant diseases; moreover, nematodes affect nutrient mobilization in C-rich soil conditions; however, information is scant on the effect of biochar addition on nematode communities. Therefore, the objective of this field study was to evaluate the influence of sugar maple hardwood biochar on soil nematode communities and assess the relation among soil nematode communities and soil nutrient concentrations. Nematode communities were sampled and identified in soils without biochar application and soil amended with an application of 8% by weight (equivalent to 160 Mg ha−1). The application of 8% biochar did not change the abundance of nematodes but affected some nematode communities. Compared to the unamended soil, biochar-amended soil had lower plant-parasitic nematode populations and higher abundance of predatory nematodes. The Shannon diversity index (H’) was lower, and the maturity index (MI) was higher with a mean value of 2.38 with biochar addition compared to 2.21 in unamended plots. Higher soil acidity and addition of substantial amounts of magnesium, calcium, potassium, and manganese in the biochar-amended soils were recorded after biochar application.

Drainage, animal manures and fungicides reduce Phytophthora wilt (caused by Phytophthora capsici) of chilli (Capsicum annuum L.) in Bhutan

Phytophthora wilt, caused by Phytophthora capsici Leon., is the most devastating disease of chilli in Bhutan. In this study, effects of bed heights to improve soil drainage, animal manures and fungicides on Phytophthora wilt on chilli were evaluated on naturally infested plots at the wet lowlands site of Bhur and in a farmer’s field at a drier, higher altitude site at Darachu in Bhutan. The experimental design was a split-plot arrangement of a randomised complete block. Bed height (flat or raised) was the main plot with amendments (poultry manure, cattle manure) or fungicide drenches (metalaxyl or potassium phosphonate) as subplot treatments. Aged manures (28,000 kg DW/ha) were applied to the field one week before planting. Chilli seedlings in the nursery bed were drenched with 1 g a.i./L potassium phosphonate or 10 mg a.i./L metalaxyl 24 hours prior to transplanting. Plant survival was significantly higher on raised beds than flat beds at Bhur (p = 0.0105), but not Darachu, although marketable yields were significantly higher on raised beds at both sites. At Darachu, poultry manure significantly improved plant survival (50%), as did cattle manure (41%) compared to unamended control plots (25%). Similar results were found at Bhur, with survival on poultry manure amended soils (40%) and cattle manure (34%), both significantly higher than on unamended soils (20%). Both fungicides significantly improved plant survival (p < 0.0001) and marketable yield (p < 0.0001) at both sites. Yields at the high-altitude, drier site at Darachu were generally higher than at the wet lowlands site at Bhur. Marketable yields on phosphonate-treated plots at both Bhur and Darachu, (16.8 and 19.1 tonnes/ha, respectively) and metalaxyl-treated plots (15.4 and 17.5 tonnes/ha) were significantly higher than on untreated plots (6.0 and 7.5 tonnes/ha). A highly significant (p = 0.0007) benefit of combining raised beds planting with manure and fungicide treatments on yield was observed at the wet lowlands site, but not at the drier site. Integrating raised bed planting with the application of poultry manure and fungicides is likely to significantly reduce yield losses of chilli due to Phytophthora wilt in different regions of Bhutan.

Differences in Physiological and Biochemical Attributes of Wheat in Response to Single and Combined Salicylic Acid and Biochar Subjected to Limited Water Irrigation in Saline Sodic Soil.

Given the expectancy of the water supply becoming scarce in the future and more expensive, water conservation during wheat production processes has become very crucial especially in saline sodic soil. Biochar and salicylic acid (SA) were used to assess the potential to alleviate the influences of depletion of available soil moisture (DAM) on physicochemical, physiological, biochemical attributes, as well as wheat production absorption (Triticum aestivum L. cv. Misr 1) and macro-elements. Two seasons (2018/2019 and 2019/2020) of field trials were investigated using twelve combinations of three water treatments (50%, 70%, and 90% DAM) and foliar- and soil-applied treatments (control, biochar, salicylic acid, and biochar + SA). Biochar treated plots amplified soil physicochemical attributes, leading to improved physiological traits and antioxidant enzymes, as well as yield related traits under water limitation conditions in both years. Similarly, synergistic use of biochar and salicylic acid greatly augmented the designed characteristics such as chlorophyll a, b, K+ content, relative water content (RWC), stomatal conductance, photosynthetic rate, and intrinsic water use efficiency, whilst exhibited inhibitory effects on proline content, electrolyte leakage, Na+ content SOD, POX, CAT, and MDA, consequently increased 1000-grain weight, number of grains spike−1, grain yield, as well nutrient uptake (N, P, K) under water limitation condition in both years, followed by treatment of sole biochar or SA compared to unamended plots treatment (control). Wheat productivity achieved further increasing at 70% DAM alongside synergistic use of biochar and SA which was on par with 50% DAM under unamended plots (control). It is concluded from the findings that coupled application of biochar alongside salicylic acid accomplished an efficient approach to mitigate the injurious influences of water limitation, along with further improvement of the soil, physiology, biochemical attributes, and wheat yield, as well nutrient uptake, under saline sodic soil.

Growth Medium and Soil Amendment Influence on Seedling Growth Responses of African Star Apple (Chrysophyllum albidum)

African Star Apple (Chrysophyllum albidum) classified as a forest food tree with economic potentials requires domestication attention for improved productivity. A study conducted in Abeokuta, Nigeria in 2017 using one year old C. albidum seedlings determined the plant’s growth responses when cultivated using different growth medium and soil amendment methods. The 3 x 9 factorial experiment was arranged in a Completely Randomized Design (CRD) at three replications. Three textural soil types (sandy, loamy and clayey soils) were evaluated using nine soil amendment methods (5, 10, 15t/ha poultry manure (PM) and 150, 250 and 500kg/ha NPK, and integrated amendment methods using 5t/ha PM+150kg/ha NPK and 10t/ha PM+150kg/ha NPK), and the un-amended plot as control. The results showed that plants in loamy and clayey soils had more leaves compared to those in sandy soil only at 74WAS. C. albidum had most numerous leaves with 150 kg/ha, taller plant and wider canopy with 250 kg/ha, and thicker girth with all NPK rates compared to control, manure rates and integrated fertilizers. The plants with loamy soil had highest CPC, Ash C, FC, starch and sugar. Plants with inorganic fertilizers and integrated fertilizers had higher FW and DW compared to manure rates. The 5 t/ha manure rate and the 250 kg/ha NPK produced plants with high sugar content and were lowest in starch content compared to other applied rates. In conclusion, C. albidum from juvenile to vegetative stage with proper management can be grown on the different soil types while the 150 kg/ha NPK fertilizer rate appeared as optimum for the plant growth.

Effect of soil fertility amendment, planting density and growing season on Chenopodium quinoa Willd (Quinoa) in Zimbabwe

Chenopodium quinoa Willd (quinoa) is a crop that originated from the Andes and has been recently introduced in Zimbabwe so the agronomic performance is unknown yet. A 3-year field experiment was carried out at the Women’s University in Africa research farm, Marondera, Zimbabwe. The research evaluated the response of quinoa to different cattle manure application rates, plant population ha−1 and growing seasons. A 3 × 3 × 2 factorial in a completely randomized block design with three replicates was used in the experiment. Cherry Vanilla Quinoa variety was established under three cattle manure application rates (0, 9 and 18 t ha−1), three planting densities (29629, 55555 and 80 000 plants ha−1) and two growing seasons per year (summer and winter). Analysis of variance was done to compare the effects of the treatments on quinoa growth parameters. There was significant (P < 0.05) interaction on cattle manure application rates × plant population ha−1 × growing season in all the measured response variables. The vegetative phase was higher on soil fertility amended than unamended plots in summer than winter regardless of the planting density. Highest grain yield (2.5 t ha−1) and thousand grain weight (T.G.W) (2.5 g) were recorded in winter at 9 t ha−1 + 55,555 plants ha−1 while lowest T.G.W (0.2 g) and grain yield (0.1 t ha−1) were noted in 18 t ha−1 + 80,000 plants ha−1 in summer. Quinoa can be grown in winter or summer with 9 t ha−1 + 55555 plants ha−1 for grain or biomass, respectively.

Soil nitrous oxide emissions associated with conversion of forage grass to annual crop receiving annual application of pig manure

The disruptive land-use change during forage grass conversion to annual crop can be critical for determining nitrous oxide (N2O) emissions, but this is an understudied period. We measured soil N2O fluxes (using closed static vented chambers) together with potential environmental drivers of these fluxes from liquid pig manure (LPM) and solid pig manure (SPM) applied to an annual crop (ANN) and perennial forages (FPP) that was converted to annual crop. Unamended plots were used as a control (CON). The results showed that in 2013, average soil nitrate-N was significantly higher on the recently converted FPP (ranging from 19 to 83 mg N kg−1) than the continuous ANN plots (from 16 to 35 mg N kg−1). The recently converted perennial forage system produced three times greater N2O than the continuous annual system, which is likely a result of accelerated N mineralization from the accumulated soil organic matter (over 4 yr) and grass residues of the recently killed forage grasses. However, during the second year of the study when the FPP plots were reseeded to perennial grasses, the system emitted 30% less N2O than the ANN system. These results suggest that including perennial forage grass in rotation with annual crops can provide N-saving and climate change mitigation benefits; however, some of the N stored in the soil would be lost when the perennial grass plots are cultivated to grow annual crops.