Effects Of Organic Amendments Research Articles

Effects of organic amendments on yield determining properties and macronutrient content of maize

The use of organic fertilization is declining in Hungary due to the sharp fall of livestock stand since the middle of the 1980s. Most farmers are forced to use solely chemical crop enhancers. A bifactorial small plot experiment was carried out between 10 May 2023 and 19 October 2023 in Keszthely, in order to examine the effects of farmyard manure (M), green manure (GM) and stem residues (SR) on the nutrient uptake and nitrogen utilization efficiencies of maize at equidistantly increasing (0–70–140–210–280 kg N ha–1) nitrogen doses. The relationship between some vegetative traits (dry biomass weight, Leaf Area Index (LAI)) and yield, furthermore leaf relative water content (RWC) was also examined. According to the results, organic fertilizer substitution significantly increased the N content both in whole plant and grain samples of NPK+M and NPK+GM+SR treatments, compared to the chemically fertilized control (NPK). In case of P and K only slight differences were observed. Whole plant K contents of NPK+M were significantly higher than in the other treatments (P = 0.045; P = 0,005), furthermore P contents in grain samples were significantly higher in NPK+M (P = 0.004) and NPK+GM+SR (P = 0.05) than in control. Harvest index (HI [%]) of NPK+M and NPK+GM+SR were 1.06 and 1.05 times higher than in NPK. Depending on the treatment, P0023 maize hybrid absorbed 58.7–74.64% of total N uptake in the grain (HIN%), and the utilization of 1 kg N fertilizer for the extra yield above the yield of the individual control was 0.39–1.38 kg (AREN). Significant positive correlations were observed between dry biomass weight and yield (NPK: r = 0.937, P = 0.019; NPK+M: r = 0.971, P = 0.006; NPK+GM+SR: r = 0.88, P = 0.049), furthermore LAI and yield (NPK: r = 0.9, P = 0.037; NPK+M: r = 0.983, P = 0.003; NPK+GM+SR: r = 0.784, P = 0.117). Highest RWC values – which may be related to better soil aggregate stability – were measured in NPK+GM+SR treatment, therefore there may be a great potential in this treatment among drought conditions. The effect of organic amendments is particularly noticeable with smaller nitrogen doses so they should be used to reduce inorganic fertilizer application and the resulting environmental risks.

Effects of Organic Amendments on the Morphology and Chemical Composition of Black Mustard (Sinapis nigra L.) Grown on Soil Contaminated with Copper

The present study aimed to determine the influence of organic amendments (OAs) on neutralizing the harmful effect of copper (Cu) on black mustard (Sinapis nigra L.). In a pot experiment, three levels of copper pollution were used: 200, 400, and 600 mg Cu kg−1, against a control without Cu. The soil was amended with three types of OAs: pine bark (PB), peat moss (PM), and cattle manure (CM). Our research showed that plant condition depends on the Cu content in the soil. Increasing soil contamination significantly affected the plant yield, leaf greenness index, and dry matter content. The type of OA had no significant effect on the condition of black mustard (BM); however, each had a different effect on neutralizing the harmful effects of Cu. CM reduced Cu accumulation, PM showed no effect, while PB contributed to a significant increase in Cu content in BM plants. The chemical composition of BM depended on the Cu content in the soil. With increased soil contamination with Cu, the contents of Ntot, K, Mg, Ca, and Na in BM increased, while the content of P decreased. In terms of mitigating the harmful effects, CM was more beneficial than PM and PB. Among the analyzed OAs, CM, and PM contributed to Cu immobilization, while PB promoted Cu mobilization in contaminated soils.

Effect of different organic amendments on phosphorus dynamics of blackgram (Vigna mungo)

Legumes play a significant role in sustainable agriculture through their ability to improve soil fertility and health. With a mutual symbiotic relationship with some bacteria in soil, they can improve nitrogen (N) amount through biological N-fixation (BNF). But to maximize such functions, legumes need more phosphorus (P) as it is required for energy transformation in nodules. Besides, P also plays a significant role in root development, nutrient uptake and growth of legume crops. A field experiment was conducted during rainy (kharif) season of 2019 at IFS unit, College of Agriculture, (University of Agricultural Sciences, Dharwad), Vijayapur, Karnataka to study the effect of different combination of organic sources on phosphorus dynamics of blackgram [Vigna mungo (L.) Hepper]. Among different treatments, the application of vermicompost + ghanajeevamrutha @ 100% RDP + Rhizobium + PSB recorded significantly higher soil available phosphorus (36.30 kg/ha) and uptake by blackgram (16.08 kg/ha). This study has demonstrated the dynamics of phosphorus through different organic sources in blackgram.

Unveiling the Synergistic Effects of Phosphorus Fertilization and Organic Amendments on Red Pepper Growth, Productivity and Physio-Biochemical Response under Saline Water Irrigation and Climate-Arid Stresses.

In regions facing water scarcity and soil salinity, mitigating these abiotic stresses is paramount for sustaining crop production. This study aimed to unravel the synergistic effects of organic matter and phosphorus management in reducing the adverse effect of saline water for irrigation on red pepper (Capsicum annuum L.) production, fruit quality, plant physiology, and stress tolerance indicators. The study was carried out in the arid Tadla region of Morocco and involved two key experiments: (i) a field experiment during the 2019 growing season, where red pepper plants were subjected to varying phosphorus fertilizer rates (120, 140, and 170 kg of P2O5.ha-1) and saline water irrigation levels (0.7; 1.5; 3; and 5 dS.m-1); and (ii) a controlled pot experiment in 2021 for examining the interaction of saline water irrigation levels (EC values of 0.7, 2, 5, and 9 dS.m-1), phosphorus rates (30, 36, and 42 kg of P2O5.ha-1), and the amount of organic matter (4, 8, 12, and 16 t.ha-1). The field study highlighted that saline irrigation significantly affected red pepper yields and fruit size, although phosphorus fertilization helped enhance productivity. Additionally, biochemical markers of stress tolerance, such as proline and glycine betaine, along with stomatal conductance, were impacted by increasing salinity levels. The pot experiment showed that combining organic amendments and phosphorus improved soil properties and stimulated red pepper growth and root weight across all salinity levels. The integration of phosphorus fertilization and organic amendments proved instrumental for counteracting salinity-induced constraints on red pepper growth and yield. Nonetheless, caution is necessary as high salinity can still negatively impact red pepper productivity, necessitating the establishment of an irrigation water salinity threshold, set at 5 dS.m-1.

Effects of Organic Amendments and Mineral Fertilizers on Optimizing Nutrient Cycling in Alkaline Soil

Soil microbial biomass carbon (MBC) and nitrogen (MBN) are indicators of microbial size and soil fertility, representing a vital living nutrient reservoir in the soil. This study aimed to evaluate the impact of various organic sources, such as poultry manure (PM), farmyard manure (FYM), compost (CM), and biochar (BC), along with different levels of mineral fertilizers on soil microbial dynamics and nutrient (N, P) mineralization through laboratory incubation experiments. The organic amendments were applied at rates of 0.25%, 0.5%, and 1.0% of soil carbon (w/w), combined with 75%, 50%, and 25% of recommended doses of NPK (120:90 and 60 kg N, P2O5, and K2O ha-1), respectively. Following the application of amendments, the soil underwent a 16-day incubation period to measure CO2 emissions and a 28-day period for N and P mineralization. The rate of CO2 evolution exhibited a significant increase with higher carbon levels but declined over time. Compost showed the highest CO2 evolution at any given time, followed by PM, FYM, and BC, likely due to a higher readily available fraction of carbon. Compost, particularly at the 1% C level in combination with inorganic fertilizer, led to a significant increase in soil microbial biomass C and N. Nitrogen and phosphorous mineralization increased with the duration of the 28-day incubation period. However, the net release of N and P decreased with higher carbon levels, potentially associated with both immobilization and the fact that higher levels received lower (25%) NPK levels. Nevertheless, soils treated with CM and PM maintained higher levels of N and P, associated with their higher fraction of labile nutrients. These findings suggest that the continuous application of organic sources enhances N and P mineralization, soil microbial biomass, and their activity. Therefore, the regular application of carbon sources emerges as a strategic approach to improving the soil health of less fertile alkaline calcareous soils.

Effect of Organic Amendments on the Speciation of Chromium in Contaminated and Uncontaminated Soils

ABSTRACT Quantitative speciation of metals and their variability over time is a critical concept in environmental soil chemistry. Chromium is a heavy metal that has negative effects on the environment and human health. There have been several attempts to study the behavior of chromium in soils and its removal from soil. However, there is relatively little knowledge about the immobilization of chromium and its chemical speciation in contaminated and uncontaminated soils when different organic amendments are applied. A laboratory incubation experiment was conducted in a completely randomized design to evaluate the effect of organic amendments on the speciation of chromium in contaminated and uncontaminated soils. Four organic amendments were used: farmyard manure (FYM), rice straw compost (RSC), vermicompost (VC), and biochar (BC). Each of them was applied at 1% to contaminated as well as uncontaminated soils. In both the amended and unamended soils, chromate (CrO4 2-), bichromate (HCrO4 −), and calcium chromate (CaCrO4) in soil-water system followed the order CrO4 2-> HCrO4 −> CaCrO4. The application of FYM, RSC, VC, and BC significantly decreased the CrO4 2- and CaCrO4 in the soil-water system of both soils. However, only the application of BC affected the HCrO4 − contaminated soils. In both soils, HCrO4 − exists as the predominant chromium species in the pH range of 2.0 to 6.25. At pH 6.25, CrO4 2- and HCrO4 − each contribute 50% of the total dissolved chromium in soil solution. CrO4 2- dominated in the system as the pH increased from 6.25 till 8.0. The maximum concentration of CrO4 2- was at pH 8.0. At pH <3.0, CrO3SO4 2- contributes less than 10%. Overall, organic amendments decreased the concentration of Cr species in both soils. However, the decrease in concentration was highly dependent on the nature of the amendment applied. Therefore, organic amendments can be exploited to remediate chromium-contaminated soils.

Effects of Land Preparation Method and Organic Soil Amendment on Soil Properties, Growth and Yield of Maize (Zea mays)

Effects of Land Preparation Method and Organic Soil Amendment on Soil Properties, Growth and Yield of Maize (Zea mays)

Inorganic carbon accumulation in saline soils via modification effects of organic amendments on dissolved ions and enzymes activities

Organic amendments are effective in promoting salt leaching, improving availability of nutrients and increasing crop yield in saline soils. However, the effects of the combined application of organic amendments on soil inorganic carbon (SIC) content and its driving mechanisms are unknown. We examined how changes in soil biochemical properties including moisture content, pH value, dissolved ions, soil organic C (SOC), dissolved organic C (DOC), microbial biomass C (MBC), and activities of C- and N-related enzyme due to applying (i) only mineral fertilizers (control; Ctrl) or mineral fertilization in combination with (ii) manure (M); (iii) biofertilizer plus manure (B+M); and (iv) humic acid plus manure (HA+M) modify SIC pool over three years. Organic amendments increased the content of Ca2+ and HCO3– ions, but significantly decreased Na+, Cl−, and SO42− at 0–60 cm soil layers compared to Ctrl. Furthermore, the activities of β-glucosidase (BG), Xylanase (BX), Cellobiosidase (CE), and β-1,4-N-Acetyl-glucosaminidase (NAG) increased at 0–40 cm soil. Partial least squares path model manifested that organic amendment directly accumulated SIC content by increasing Ca2+ content and the activities of BX and NAG. Additionally, the decrease of Cl− contents under organic amendments favored the increase of MBC and SOC content, which further increased SIC content. Generally, the effects of HA+M were greater than other fertilization managements, which increased the stocks of SIC and total C at 0–60 cm soils by 27 Mg ha−1 and 47 Mg ha−1, respectively. Furthermore, the effect of organic amendments on SIC content is more pronounced below the first 20 cm. Thus, the application of organic amendments is recommended as an appropriate measure to not only improve soil condition for plant growth and SOC accumulation but also to store C as SIC at deeper depths.

Comparison of the Effects of Different Organic Amendments on the Immobilization and Phytoavailability of Lead

Organic materials, such as straw, animal manure, and their processed product biochar, are known to exhibit agronomic effects and the ability to remediate heavy metal contamination. However, knowledge regarding the relative effects of different organic amendments in soils on heavy metal immobilization and phytoavailability remain limited. Consequently, the effects of maize straw (MS), chicken manure (CM), mushroom cultivation waste (MW), and sawdust biochar (SB) on the immobilization and phytoavailability of lead (Pb) in wheat plants were investigated in this study using pot experiments. The results showed that the artificial application of Pb reduced soil pH, while increasing the total organic carbon (TOC) and cation exchange capacity (CEC) to various extents. Furthermore, the Pb treatment increased the adsorption of Pb by wheat grains (0.83 mg∙kg−1), resulting in decreased above-ground dry biomass (43.16 g∙pot−1) during the maturity growth period when compared with the control check (CK) treatment. The MS + Pb and CM + Pb treatments increased the exchangeable Pb fractions in the soil, but had a limited effect on Pb accumulation in wheat grains compared with the Pb treatment. In contrast, the SB + Pb treatment effectively increased soil pH and TOC, while decreasing the fraction of exchangeable Pb forms and increasing the oxidizable and residual Pb fractions, compared with the Pb treatment. Moreover, the MW + Pb treatment also increased the soil pH and CEC, displaying the potential to increase soil TOC, in addition to substantially modifying the portioning of Pb from exchangeable forms to less bioavailable fractions. Both the MW and SB amendments significantly reduced Pb concentrations in wheat grains (0.49 and 0.70 mg∙kg−1,∙respectively), resulting in increased above-ground dry biomass (51.59 and 54.12 g∙pot−1, respectively). In summary, the application of organic amendments, especially MW, could be an effective measure for enhancing Pb immobilization in polluted soils, thereby reducing its uptake and translocation to crops.

Greenhouse gas emissions, carbon stocks and wheat productivity following biochar, compost and vermicompost amendments: comparison of non-saline and salt-affected soils

Understanding the impact of greenhouse gas (GHG) emissions and carbon stock is crucial for effective climate change assessment and agroecosystem management. However, little is known about the effects of organic amendments on GHG emissions and dynamic changes in carbon stocks in salt-affected soils. We conducted a pot experiment with four treatments including control (only fertilizers addition), biochar, vermicompost, and compost on non-saline and salt-affected soils, with the application on a carbon equivalent basis under wheat crop production. Our results revealed that the addition of vermicompost significantly increased soil organic carbon content by 18% in non-saline soil and 52% in salt-affected soil compared to the control leading to improvements in crop productivity i.e., plant dry biomass production by 57% in non-saline soil with vermicompost, while 56% with the same treatment in salt-affected soil. The grain yield was also noted 44 and 50% more with vermicompost treatment in non-saline and salt-affected soil, respectively. Chlorophyll contents were observed maximum with vermicompost in non-saline (24%), and salt-affected soils (22%) with same treatments. Photosynthetic rate (47% and 53%), stomatal conductance (60% and 12%), and relative water contents (38% and 27%) were also noted maximum with the same treatment in non-saline and salt-affected soils, respectively. However, the highest carbon dioxide emissions were observed in vermicompost- and compost-treated soils, leading to an increase in emissions of 46% in non-saline soil and 74% in salt-affected soil compared to the control. The compost treatment resulted in the highest nitrous oxide emissions, with an increase of 57% in non-saline soil and 62% in salt-affected soil compared to the control. In saline and non-saline soils treated with vermicompost, the global warming potential was recorded as 267% and 81% more than the control, respectively. All treatments, except biochar in non-saline soil, showed increased net GHG emissions due to organic amendment application. However, biochar reduced net emissions by 12% in non-saline soil. The application of organic amendments increased soil organic carbon content and crop yield in both non-saline and salt-affected soils. In conclusion, biochar is most effective among all tested organic amendments at increasing soil organic carbon content in both non-saline and salt-affected soils, which could have potential benefits for soil health and crop production.

Effects of organic amendments, biofertilisers and biodynamic preparations on soil properties and leaf nutrient concentrations in grapevine

ABSTRACT Excessive and unbalanced use of chemical fertilisers can lead to depletion of physical and chemical properties of the soil and have negative impacts on the environment. This investigation was conducted at Mizoram University, Aizawl, Mizoram, India and aimed to evaluate effects of organic amendments, biofertilisers and biodynamic preparations on soil properties and leaf nutrient status of grapevine. The experiment was laid out in randomised block design with 14 treatments consisting of different combinations of organic amendments, biofertilisers and biodynamic preparations viz. farmyard manure (FYM), vermicompost (VC), pig manure (PIM), neem cake (NC), Azospirillum, phosphate solubilising bacteria (PSB), potash solubilising bacteria (KSB), Trichoderma harzianum, cow pat pit (CPP) and biodynamic preparations BD500 and BD501. The results demonstrated that the use of organic amendments in combination with biofertilisers and biodynamic preparations enhanced leaf nutrient status as well soil properties in the vineyard. Among all the tested combinations, the highest concentrations of Mn, Zn, chlorophyll a, b and total chlorophyll in the leaves and concentrations of soil organic carbon, inorganic carbon, total carbon, total N, available N, P, K, Mn and Zn, cation exchange capacity (CEC) and abundance of bacteria and Actinomycetes in the soil were recorded with application of PIM + Azospirillum + PSB + KSB + T. harzianum + CPP + BD 500 + BD 501. This treatment was therefore recommended as a suitable option to meet the demand for long-term maintenance of soil fertility as well agroecosystem conservation and sustainability.

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.

Assessment of the Change in Soil Properties and Aggregates Formation of Freshly Restored Texturally Different Marginally Salt-Affected Soils Under Various Soil Amelioration Strategies

ABSTRACT Climate change and salt-affected soils detrimentally affect crop production in arid regions. Reclaiming these soils for crops and carbon sequestration can mitigate climate change and enhance food security. A laboratory-scale experiment was conducted on a wheat-maize crop rotation system for three consecutive years to check the effectiveness of organic amendments in reclaiming marginally salt-affected soils, improving soil health, sequestering carbon, and improving food grain production. This study included five treatments namely control (T1), gypsum alone at 100% gypsum requirements (G100), and its combinations with different organic amendments and 50% gypsum requirements (farm manure (FYM+G50), poultry manure (PM+G50), and green manure (GM+G50)) were used. Results indicated that sandy clay loam textured soil showed highest potential for its properties improvement after 45 days, i.e., EC decreased up to 3.9 dS m−1, pH 7.9 and, SOC increase up to 0.25%. After the fallow period, three consecutive years of crop production study indicated up to 39 and 70% increase in wheat and maize yields, respectively, compared to inorganic fertilizer alone. Maximum soil aggregation was noted in treatment with gypsum and farmyard manure application in loam soils (50%). The maximum soil organic carbon accumulation over the whole experiment was recorded in farmyard manure application in combination with gypsum (0.44 g kg−1) in both loam and sandy clay loam soil, while 0.31 g kg−1 in the clay loam soil. Based on the results, it was concluded that reclaiming marginally salt-affected soils enhances food crop production and incorporating manures improves soil through aggregation and carbon sequestration, mitigating climate change.

Impact of biochar and organic fertilizers on sweet potato yield, quality, ascorbic acid, β-carotene, sugars, and phenols contents

ABSTRACT The demand for food is increasing and the use of soil organic amendments in agricultural management practices has been instructed to increase crop yield and reduce dependence on synthetic inorganic fertilizers at low cost to limited resource farmers. However, the effect of organic amendments on the quality and nutritional composition of edible plants has received little attention. Locally available organic amendments (sewage sludge SS, chicken manure CM, cow manure Cow, vermicompost Vermi, and biochar Bio) were chosen to test their impact on field-grown sweet potato, Ipomoea batatas L. yield, root quality, and root nutritional composition. The results indicated that utilizing Cow manure in growing sweet potatoes significantly promoted root yield and root nutritional composition. Cow treatment produced the greatest number of roots compared to Bio, CM, SS, and the control treatments. The results also revealed that the concentrations of vitamin C (260. 3 µg g−1), β-carotene (45.4 µg g−1), soluble sugars (16.7 mg g−1), and total phenols (196.3 3 µg g−1 fresh roots) were greater in the roots of plants grown in Cow compared to the roots of the control treatment. The results indicated the low impact of biochar whereas Cow is recommended for enhancing sweet potato yield and nutritional composition.

Changes in Microbial Community and Activity Caused by Application of Silkworm Excrement and Biochar Under Atrazine Stress in Soil

ABSTRACT Silkworm excrement (SE) and silkworm excrement-derived biochar (BC) were applied to atrazine-contaminated soil at the rates of 0% and 0.5% (w/w), respectively. The effect of organic amendments on sorption capacity, microbial biomass carbon, enzyme activity (dehydrogenase, urease and catalase) and bacterial composition in soil were evaluated. Atrazine significantly decreased the microbial activity and diversity in soil. Both SE and BC treatments increased the sorption of atrazine in soil. SE treatment significantly increased the microbial biomass carbon and enzyme activity in contaminated soil. Unlike the addition of silkworm excrement, BC treatment had no significant effect on dehydrogenase activity. Additionally, Illumina-MiSeq sequencing analyses showed that the two organic amendments increased the Shannon index of bacteria. SE treatment improved the relative abundance of Bacteroidetes. BC treatment improved the Proteobacteria in atrazine contaminated soil.

Long-term organic amendments increase the vulnerability of microbial respiration to environmental changes: Evidence from field and laboratory studies

Organic amendments can improve soil fertility and microbial diversity, making agroecosystems more resilient to stress. However, it is uncertain whether organic amendments will enhance the functional capacity of soil microbial communities, thereby mitigating fluctuations in microbial respiration caused by environmental changes. Here, we examined the impacts of long-term organic amendments on the dynamics of microbial catabolic capacity (characterized by enzyme activities and carbon source utilization) and microbial respiration, as well as their interrelationships during a period with fluctuating temperature and rainfall in the field. We then subjected the field soil samples to laboratory heating disturbances to further evaluate the importance of microbial catabolic capacity in explaining patterns of microbial respiration. In both field and laboratory experiments, organic amendments tended to increase the stability of microbial catabolic capacity, but significantly increased the vulnerability of microbial respiration to environmental changes. However, the direction and driving factors of microbial respiration affected by environmental changes differed between the field and laboratory experiments. Environmental changes in the field suppressed the promotional effects of organic amendments on microbial respiration mainly through reducing microbial catabolic capacity, while laboratory heating further enhanced microbial respiration mainly due to increased soil resource availability. Together, these findings suggest that increased microbial respiration variations under organic amendments may potentially increase the uncertainty in predicting soil carbon emissions in the scenario of ongoing climate/anthropogenic changes, and highlight the necessity of linking laboratory studies on environmental changes to field conditions.

Cationic micronutrient fractions in some tropical Alfisols and Inceptisols as affected by organic amendments and simulated moisture regimes: an incubation study

Cultivation of rice is severely jeopardized by the intangible behavior of micronutrients under variable moisture and organics leading to its inconsistent availability. The present study has been conducted to determine the effect of organic amendments and moisture regimes on cationic micronutrients like zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). Controlled situation incubation study using thrice replicated factorial randomized design with (3 organic amendments × 2 moisture regimes × 2 incubation periods) levels was conducted. Continuous submergence (CS), 50 g kg−1 rice straw and 150 days of incubation (DOI) restored higher soluble and Exchangeable (SE) manganese and iron; while SE-Cu was facilitated under alternate wetting and drying (AWD) condition. SE-Zn was found higher under AWD, no organic administration and 60 DOI. Again AWD, 50 g kg−1 rice straw and 60 DOI recovered higher Mn, Cu, Fe and Zn in organically bound fractions. The adoption of CS, 50 g kg−1 rice straw and 150 DOI recovered higher Mn, Cu, Fe and Zn in manganese and amorphous iron oxide bound fractions; while AWD, no rice straw administration and 60 DOI recovered higher Mn, Cu, Fe and Zn in crystalline iron oxide bound fractions. Substantial change in all the studies fraction resulted into alteration in plant availability of Mn, Cu, Fe and Zn. Under the scenario of global increasing water demands, AWD apart from saving 30-40% moisture improves availability of Cu and Zn which is further accentuated by organic matter, sustaining soil productivity and ensuring food security.

Influence of Date Palm-Based Biochar and Compost on Water Retention Properties of Soils with Different Sand Contents

Generally, soils of arid and semi-arid regions have low water retention properties due to high sand and low organic carbon contents. This study aimed at quantifying the effect of date palm-based organic amendments (OAs) on the water retention properties of two soils (sandy loam and silty loam), as well as the influence of sand supplementation (0.5–2 mm) on the magnitude of the effect of OAs. Different grain size distributions were obtained by adding sand to natural soils. For this purpose, sand was added to the two soils (1/3 and 2/3) and different soil-OA combinations were tested at a dose of 3% by mass: compost alone, biochar alone and a mixture of biochar and compost (50:50 in mass), in addition to unamended control soils. Soil water contents were measured at nine matric potentials ranging from the saturation to the permanent wilting point. Biochar was more efficient than compost at improving soil water retention. The effect of organic amendments on water retention increased with sand content. In most cases, soil water content values were significantly higher for biochar-amended soils than for unamended or compost-amended soils. The weakness of the effect of compost addition (if alone) was probably due to its properties and notably its high mineral content and electrical conductivity. Soil sand supplementation led to higher differences between the OA-amended soils and unamended soils. Changes in available water capacity reached +26% and +80% in a sandy loamy soil enriched with 2/3 sand and amended with compost and with biochar, respectively, compared to the unamended soil. These results show that sand content (and more generally, soil texture) influences the effect of OA application. Thus, the application of biochar from date palm residues in soil seems to be an effective solution to improve the water retention properties of coarse textured soils and contribute to optimizing the use of water resources in irrigated areas.

Optimizing maize productivity: A sustainable approach integrating straw derivatives and film mulching in rainfed agriculture

Context or problemResource-use inefficiency, environmental degradation and food security are forcing a transformation from conventional to organic and sustainable agriculture. Objective or research questionRealizing synergistic use of light, water, and nitrogen resources for spring maize in a more circular straw utilization model, while comprehensively evaluating the sustainability of the scheme is the key to solving the above problems in rainfed areas, but there are few reports. MethodsAccording to a crop-livestock-biogas digester straw recycling model, straw can be returned to the field directly or in the form of cattle manure after fattening, or cattle manure can continue to be recycled by the digester as the only fermentation substrate, and ultimately returned to the field indirectly in the form of biogas residue. Therefore, according to different levels of straw recycling, four treatments were set up in this study: straw (S), cattle manure (M), biogas residue (BR) and control (CK) for a comparative study of water use efficiency, net solar radiation use efficiency, photosynthetic and leaf characteristics post-anthesis, annual nitrogen balance, spring maize yield, and sustainability index. ResultsThe results showed that straw and its derivatives effectively improve the utilization efficiency of light and water, potentially reducing the adverse effects of factors on yield variability. Maintaining high levels of photosynthetic activity after anthesis was mainly due to the positive effects of organic amendments on nitrogen content per unit leaf area. This led to significant increases in grain yield and harvested index by 5.95% to 13.22% and 3.41% to 6.37%, respectively. However, exogenous organic N addition promoted N2O emission and NH3 volatilization, resulting in a higher N surplus. The sustainable index of each treatment was in the following order: BR>M>CK>S. ConclusionsLong-term organic amendments, especially BR, can effectively improve the utilization and synergistic effects of critical production resources, constituting a high-yielding, efficient and sustainable spring maize population, which is consistent with our hypothesis that the sustainability index is higher in more circular straw utilization. Implications or significanceThis study provides a new plastic film cultivation strategy and evaluation perspective for sustainable spring maize production in the study area or similar areas.

Effect of composite organic amendment on Cd(II) ions stabilization and microbial activity under various ammonium sulfate levels

To attenuate the risk of Cadmium(Cd) contamination and the deterioration of soil quality caused by excessive nitrogen fertilizer application in greenhouse, a composite organic amendment (spend mushroom substrate and its biochar) was prepared to remedy Cd(II) ions contaminated soil (0.6 mg/kg) under different N fertilizer levels. The results showed that in the absence of a composite organic amendment, the soil pH decreased by 0.15 when the N level increased from 0.1 to 0.8 g N⋅kg−1. However, the pH increased by 0.86–0.91, the exchangeable Cd(II) ions content decreased by 26.0%–26.7%, the microbial biomass increased by 34.34%–164.46%, and the number of copies of the AOB gene increased by 13–20 times with the application of composite organic amendment and the increase of N level. Both Pearson correlation analysis and Mantel test demonstrated the reduction in Cd(II) ions availability, the restoration of soil properties and the increase in microbial biomass all contributed to the composite organic amendment, which is of importance for soil remediation under excessive N fertilizer.