Organic Inorganic Fertilizers Research Articles

Long-term organic fertilizer and biofertilizer application strengthens the associations between soil quality index, network complexity, and walnut yield

Although various combinations of organic-inorganic fertilizers can enhance plant yields, the effects of different fertilization regimes on the associations between rhizosphere soil microorganisms and plant productivity are poorly understood. In this study, we investigated the rhizosphere soil microbial composition and structure and the relationships among rhizospheric microorganisms, soil properties, and yield in a walnut (Juglans regia L.) orchard after 7 years of applying different fertilization regimes. The combinations of organic and inorganic fertilizers were found to enhance walnut yield, soil quality index (SQI), and soil biodiversity (bacterial and fungal) (P < 0.05). The soil microbial community composition and co-occurrence networks of rhizosphere soil (RS) and bulk soil (BS) showed different responses to fertilization. Bacillus and Pseudomonas were mainly enriched in RS, whereas Fusarium was significantly more abundant in BS (P < 0.05) under a combined chemical fertilizer, organic fertilizer, and biofertilizer treatment (F + O + BO). Network analysis revealed that organic fertilizer and biofertilizer reduced the competition and network complexity among rhizosphere microbial communities (edges: RS = 388, BS = 967; modularity: RS = 0.790, BS = 0.834). Furthermore, SQI, microbial diversity, and network complexity were significantly correlated with walnut yield (P < 0.01), among which SQI explained the highest proportion of the variation in yield (SOI: RS = 78.02%; BS = 81.18%). In addition, both yields and soil microbial community composition were significantly affected by pH, SOM, TN, and SMBN. Collectively, these findings have important implications for our understanding of the relationship between woody plants and rhizospheric microorganisms.

Effects of Long-Term Organic–Inorganic Nitrogen Application on Maize Yield and Nitrogen-Containing Gas Emission

A sustainable model of combined organic–inorganic fertilizer application for high maize yields and environmental health is important for food security. The short-term combined application of organic and inorganic fertilizers can improve crop yields; however, the effect of different proportions of organic and inorganic fertilizers on the maize yield and nitrogen gas emissions in a long time series has not been reported. In this study, field experiments and DeNitrification-DeComposition (DNDC) model simulations were used to study the long-term effects of substituting inorganic fertilizers with organic fertilizers on crop yields and nitrogen-containing gas emissions. Six treatments were included: no nitrogen (CK); urea (U1); and 25%, 50%, 75%, and 100% of the urea N substituted by organic fertilizers (U3O1, U1O1, U1O3, and O1, respectively). The DNDC model was calibrated using the field data from the U1 treatment from 2018 to 2020 and was validated for the other treatments. The results showed that this model could effectively simulate crop yields (e.g., nRMSE &lt; 5%), soil NH3 volatilization, and N2O emissions (nRMSE &lt; 25%). In addition, long-term (26 years) simulation studies found that the U1O1 treatment could considerably increase maize yields and ensure yield stability, which was 15.69–55.31% higher than that of the U1 treatment. The N2O, NH3, and NO emissions were in the descending order of U1 &gt; U3O1 &gt; O1 &gt; U1O3 &gt; U1O1, and the total nitrogen-containing gas emissions from the U1O1 treatment decreased by 53.72% compared with the U1 treatment (26 years). Overall, substituting 50% of inorganic nitrogen with organic nitrogen could maintain the high yield of maize and reduce emissions of nitrogen-containing gases, constituting a good mode for the combined application of organic–inorganic nitrogen in this area.

Does Co-Application of Compost and Mineral Fertilizers Reduce Gaseous Nitrogen (NH3 and N2O) Losses and Improve Nitrogen Use Efficiency from Maize-Growing Soil?

Nitrogen (N) has been considered one of the vital elements to enhance agricultural productivity. However, excessive use of N fertilizer can deteriorate environmental quality, increasing ammonia (NH3) and greenhouse gases (GHGs) emissions from agricultural ecosystems. The combined use of inorganic and organic fertilizers may improve nutrient holding capacity, which can potentially reduce N losses (NH3 and N2O), resulting in high N use efficiency (NUE) and crop productivity. To investigate gaseous N losses and NUE in a maize (Zea mays L.) field experiment, four treatments for N fertilizers were laid out: NPK (urea), compost (compost), NPK+Compost (urea and compost), and control (no fertilizer) treatments. As compared to the control, seasonal NH3 emissions significantly increased with all fertilization. In particular, combination of organic and inorganic fertilizers was effective on reducing N losses including NH3 volatilizations and N2O emissions, showing ca. 16% and 47% reduction, respectively over sole NPK treatment even though the same amount of N was incorporated in all treatments except the control. Maize productivity was significantly improved by N fertilizations, but was the highest in the NPK+Compost treatment, showing no statistical difference with NPK treatment. The NUE was the highest in the NPK treatment (35%) and followed by NPK+Compost (27%), compost (11%), respectively. In conclusion, mixing of organic-inorganic fertilizers could be a reasonable countermeasure to reduce the loss of gaseous N and simultaneously maintain productivity and NUE in agricultural soils.The amount of ammonia volatilization, nitrous oxide emission and total gaseous N losses at different N fertilization regimes from maize-growing soil. Treatments Total N input (kg ha-1) NH3-N loss (kg ha-1) N2O-N loss (kg ha-1) Total N losses (kg ha-1) (%) Control - 4.24 c† 0.84 b 5.08 c - NPK 158 6.74 a 2.93 a 9.66 a 6.11 a Compost 158 4.50 c 1.44 b 5.94 c 3.76 b NPK+Compost 158 5.64 b 1.55 b 7.19 b 4.55 b †Different letters for each row showed a significant difference at p ≤ 0.05 according to LSD’s test.

Soil Nutrient Content Analysis of Newly-Increased Farmland in the Process of Land Consolidation In Shaanxi Province, China

The aim of this study is to analyze the characteristics of soil nutrient content of newly increased cultivated land in land consolidation, and identify the main factors affecting the productivity of newly increased cultivated land. The soil samples of 101 newly added cultivated land in northern, central and southern Shaanxi were collected, and their pH value, organic matter, total nitrogen, available phosphorus and available potassium contents were measured to analyze the soil nutrient status. The results indicated that the contents of soil organic matter, total nitrogen, available phosphorus and available potassium in the newly increased cultivated land were 0.21~23.63 g/kg, 0.20~8.27 g/kg, 2.34~34.16 mg/kg and 51~220 mg/kg, respectively. Compared with the nutrient grading standard of the second national soil survey, the content of soil nutrients in the newly increased cultivated land was relatively low, basically at the level of four to six. It was also revealed that Tte soil nutrient content of newly increased cultivated land in Shaanxi Province is greatly affected by the original land use types in northern Shaanxi and Guanzhong, and the soil nutrient difference in southern Shaanxi is mainly caused by the random changes among plots in the same region; The variance test showed that there were significant differences in soil pH organic matter and available potassium at 0.05 level, but no significant differences in soil total nitrogen and available phosphorus at 0.05 level. (3) It can be seen from the correlation analysis that among the nutrient indicators of the newly increased farmland in Shaanxi, pH organic matter has a significant negative correlation, and organic matter available potassium and available phosphorus available potassium have a very significant correlation. The correlation between soil nutrients in the newly increased farmland is weak, and the coordination between nutrients is poor. The low content of organic matter in soil is the main reason for low fertility. In the later stage of utilization, it is necessary to promote straw returning technology through the reasonable application of organic inorganic fertilizer and the application of soil testing formula fertilization technology, so as to finally realize the stable and high yield of newly added farmland. Bangladesh J. Bot. 51(4): 1017-1028, 2022 (December) Special

Emissions of Greenhouse Gases and Ammonia From a Wheat Site Under Intensive Management Affected by Different Fertilization Practices

Highlights The recommended mineral fertilizers plus organic fertilizer treatments increased the soil total carbon (TC) and nitrogen (TN) levels. The application of organic fertilizer markedly reduced the loss of NH3-N compared to the application of mineral nitrogen alone. CO2 and N2O emissions from the application of organic fertilizer were higher than those from the application of mineral nitrogen under long-term fertilization. Abstract. Greenhouse gas (GHG) and ammonia (NH3) emissions from wheat fields have been a serious challenge to agriculture and the environment. The integration of the use of inorganic N fertilizer, organic fertilizer, and crop residues and their environmental effects is needed under conventional tillage. In situ field experiments were established to evaluate the impact of different fertilization practices on soil greenhouse gas and ammonia emissions from a winter wheat field. A fertilizer experiment was performed from 24th October 2019 to 11th June 2020 in a winter wheat (Triticum aestivum L.) field in China with six fertilization treatments: (1) unfertilized control (UC); (2) recommended mineral fertilizer application of 200 kg ha-1 N (RF); (3) RF plus 15 t ha-1 of organic fertilizer (RFLO); (4) RF plus 30 t ha-1 of organic fertilizer (RFMO); (5) RF plus 45 t ha-1 of organic fertilizer (RFHO); and (6) traditional mineral fertilizer application of 300 kg ha-1 N (TF). The results showed that the RF plus organic fertilizer treatments increased the soil organic total carbon (TC) and nitrogen (TN) levels. Under long-term fertilization, the CO2 emissions from the RFLO, RFMO, and RFHO treatments were 18.3, 19.9, and 20.0 t ha-1, respectively, compared with those from the RF and TF treatments (13.2 and 16.0 t ha-1, respectively). In addition, the N2O emissions from the organic-inorganic fertilizer treatment were 7.6 kg ha-1 for the RFLO treatment, 12.4 kg ha-1 for the RFMO treatment, and 8.1 kg ha-1 for the RFHO treatment, which were higher than those from the RF and TF treatments (3.1 and 5.6 kg ha-1, respectively). The NH3 emissions from the RFLO, RFMO, and RFHO treatments (17.3, 26.2, and 22.4 kg ha-1, respectively) were lower than those from the RF (31.2 kg ha-1) and TF (49.7 kg ha-1) treatments under long-term fertilization. The methane emission potential of organic-inorganic fertilizer applications was 27.0% to 98.5% higher than a single application of inorganic fertilizer. Keywords: Ammonia, Carbon dioxide, Fertilization management, Nitrous oxide, Organic fertilizers, Winter wheat.

Combined organic-inorganic fertilization builds higher stability of soil and root microbial networks than exclusive mineral or organic fertilization

Plant health and performance are highly dependent on the root microbiome. The impact of agricultural management on the soil microbiome has been studied extensively. However, a comprehensive understanding of how soil types and fertilization regimes affect both soil and root microbiome is still lacking, such as how fertilization regimes affect the root microbiome’s stability, and whether it follows the same patterns as the soil microbiome. In this study, we carried out a long-term experiment to see how different soil types, plant varieties, and fertilizer regimens affected the soil and root bacterial communities. Our results revealed higher stability of microbial networks under combined organic-inorganic fertilization than those relied solely on inorganic or organic fertilization. The root microbiome variation was predominantly caused by total nitrogen, while the soil microbiome variation was primarily caused by pH and soil organic matter. Bacteroidetes and Firmicutes were major drivers when the soil was amended with organic fertilizer, but Actinobacteria was found to be enriched in the soil when the soil was treated with inorganic fertilizer. Our findings demonstrate how the soil and root microbiome respond to diverse fertilizing regimes, and hence contribute to a better understanding of smart fertilizer as a strategy for sustainable agriculture.

Determining organic-inorganic fertilizer application threshold to maximize the yield and quality of drip-irrigated grapes in an extremely arid area of Xinjiang, China

Imbalanced water and fertilizer systems have limited the yield and quality of grapes in extremely arid areas. The combined application of organic (OF) and inorganic fertilizers (CF) has been proven to be one of the practical approaches to improving yield and quality. Nevertheless, very few studies have focused on the irrigation amount in organically fertilized and drip-irrigated grapes. Hence, in this study, four combined application ratios of organic and inorganic fertilizers (70%OF + 30%CF, 50%OF + 50%CF, 30%OF + 70%CF, and 0%OF + 100%CF), and four irrigation amounts (630, 675, 720, and 765 mm) were set coupling in a two-year field experiment. Generally, under four irrigation levels, combined organic-inorganic fertilizers increased soil nutrients and improved seedless white grape growth, yield, and quality. The results of the combined fertilizer application treatments showed that the content of available nitrogen (55.97–102.60%), available phosphorus (49.41–124.74%), and available potassium (60.70–124.33%) in soil increased significantly compared with those values under a single application of inorganic fertilizer. In addition, the combined application increased the length of new shoots and leaf midribs (grapes) by 3.16–11.88% and 7.35–15.15%, respectively; this application mode also significantly enhanced transpiration rate (Tr), stomatal conductance (Gs), and net photosynthetic rate (Pn). Furthermore, the grape yield increased by 6.68–19.12%, and the fruit quality notably improved (except for the index of fruit shape). Under the four irrigation amounts, two-year average yields were reported as 17.53, 20.60, 23.31, and 22.71 kg/ha, respectively. Additionally, we used four evaluation methods to assess the fruit quality and compared their correlations with the comprehensive evaluation model. And we concluded that the principal component analysis method (PCA) is best suited for evaluating drip-irrigated grapes’ quality. Then, we applied the PCA to seek proper irrigation management; the results displayed that a suitable irrigation amount of 720 mm and the ratio of organic-inorganic application of 50% organic fertilizer + 50% inorganic fertilizer is recommended. However, further research is required to investigate the effects of soluble and complete organic fertilizers application on drip-irrigated grapes.

Changes in the Physical, Chemical, and Bacterial Community Characteristics of Soil in Response to Short-Term Combined Organic–Inorganic Fertilizers in a Dry Direct-Seeded Paddy Field

Dry direct-seeded rice cultivation is a simple and labor-saving planting method wherein the combined application of organic and inorganic fertilizers can improve yield. However, the effects of combined fertilizers on soil properties and bacteria in dry direct-seeded rice paddy soil are unclear. Here, four treatments, conventional fertilization (NPK), seaweed bio-organic fertilizer + NPK, Jishiwang bio-organic fertilizer + NPK, and attapulgite organic fertilizer + NPK applied for three consecutive years were tested to explore their effects on soil physical, chemical, and bacterial community characteristics in a dry direct-seeded rice paddy field. The combined fertilizers increased alkaline hydrolysis-nitrogen and available potassium while decreasing the bulk density and pH; in addition, a marked increase in the relative abundance of soil macroaggregates (&gt;5 mm) and clay particles and a decrease in that of sand was observed. Urease and neutral phosphatase activities were the highest with the Jishiwang organic fertilizer + NPK, whereas invertase and catalase activities were the highest with attapulgite organic fertilizer + NPK. All combined fertilizers considerably increased the bacterial richness index (ACE) and Chao index; Jishiwang bio-organic fertilizer + NPK also increased the Simpson index, whereas the seaweed bio-organic fertilizer + NPK reduced it. Proteobacteria and Acidobacteria accounted for 54.25–70.49% of the total bacterial relative abundance. The relative abundance of Verrucomicrobia, Chloroflexi, Firmicutes, and Nitrospirae increased with the combined fertilizers. The correlation network analysis showed predominant antagonistic relationships. A redundancy analysis demonstrated that total nitrogen, soil organic matter, urease, and invertase were the main environmental factors affecting bacterial composition. Combined fertilizers may improve soil physical and chemical properties, fertility, and bacterial richness.

Role of fertilization regime on soil carbon sequestration and crop yield in a maize-cowpea intercropping system on low fertility soils

Achieving food security through intensive agricultural practices on low fertility soils is challenging as crop productivity is increasingly curtailed by the loss of soil structural stability and rapid depletion of soil organic carbon (SOC). As such, the conversion from traditional mono-cropping to legume-cereal intercropping, especially with integrated fertilization, may increase crop yields with the least ecological footprint. We set up a 2-year field experiment in a split-plot design with cowpea-maize monoculture and intercropping under different organic–inorganic fertilization regimes, including no fertilization (control), organic input only (compost), chemical input only (NPK), and multi-nutrient enriched compost (NPKEC). We observed that intercropped maize had a significantly higher biomass yield compared to the corresponding monoculture when fertilized with NPKEC fertilizer. However, cowpea biomass yield differences between monoculture and intercropped plots were comparable under all fertilization regimes. In contrast, the grain yield advantage of both maize and cowpea was significantly enhanced under the intercropping system compared to monoculture, with NPKEC showing the most significant effect among all fertilization regimes. When comparing the relative contribution of the fertilization regime to SOC, the NPKEC fertilizer provided the highest SOC-sequestration (0.30 Mg C/ha yr−1). At the same time, the effect of the cropping system on C-sequestration showed that intercropping provided the highest C-sequestration (0.17 Mg C/ha yr−1) compared to monocultures of both crops. Although compost application significantly increased mineral associated (MAOC) and particulate associated organic carbon (PAOC) concentrations compared to unfertilized control plots, NPKEC fertilization with intercropping system was the most effective combination causing the greatest increase of both soil C pools over time. Based on redundancy analysis (RDA), the positive association of MAOC and PAOC with C-sequestration suggests the importance of both organic fractions as primary C reservoirs conducting SOC storage. Importantly, although compost alone in association with intercropping had a lower C-sequestration, it was associated to a better soil structure as confirmed by its positive relationship with macro-and micro-aggregation, water stable aggregates (WSA), and mean weight diameter (MDA). Overall, our results indicate the importance of restoring soil structure in degraded soils through appropriate land management solutions, such as stoichiometrically balanced fertilization practices (NPKEC) and crop diversification (intercropping), in order to achieve significant gains in SOC storage and, ultimately, improve crop productivity.

Dynamic of bacterial and archaeal diversity in a tropical soil over 6 years of repeated organic and inorganic fertilization.

The soil microbial community plays important roles in nutrient cycling, plant pathogen suppression, decomposition of residues and degradation of pollutants; as such, it is often regarded as a good indicator of soil quality. Repeated applications of mixed organic and inorganic materials in agriculture improve the soil microbial quality and in turn crop productivity. The soil microbial quality following several years of repeated fertilizer inputs has received considerable attention, but the dynamic of this community over time has never been assessed. We used high-throughput sequencing targeting 16S ribosomal RNA genes to investigate the evolution of the bacterial and archaeal community throughout 6 years of repeated organic and inorganic fertilizer applications. Soils were sampled from a field experiment in La Mare (Reunion Island, France), where different mixed organic-inorganic fertilizer inputs characterized by more or less stable organic matter were applied regularly for 6 years. Soil samples were taken each year, more than 6 months after the latest fertilizer application. The soil molecular biomass significantly increased in some organically fertilized plots (by 35–45% on average), 3–5 years after the first fertilizers application. The significant variations in soil molecular microbial biomass were explained by the fertilization practices (cumulated organic carbon inputs) and sometimes by the soil parameters (sand and soil carbon contents). The structure of the bacterial and archaeal community was more influenced by time than by the fertilization type. However, repeated fertilizer applications over time tended to modify the abundance of the bacterial phyla Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. To conclude, the present study highlights that the soil bacterial and archaeal community is lastingly modified after 6 years of repeated fertilizer inputs. These changes depend on the nature of the organic input and on the fertilization practice (frequency and applied quantity).

Effects of biochar and organic-inorganic fertilizer on pomelo orchard soil properties, enzymes activities, and microbial community structure.

Fertilizer management can influence soil microbes, soil properties, enzymatic activities, abundance and community structure. However, information on the effects of biochar in combination with organic-inorganic fertilizer after 3 years under pomelo orchard on soil bacterial abundance, soil properties and enzyme activities are not clear. Therefore, we conducted a field experiment with seven treatments, i.e., (1) Ck (control), (2) T1 (2 kg biochar plant–1), (3) T2 (4 kg biochar plant–1), (4) T3 (2 kg organic-inorganic mixed fertilizer plant–1), (5) T4 (4 kg biochar + 1.7 kg organic-inorganic mixed fertilizer plant–1), (6) T5 (4 kg biochar + 1.4 kg organic-inorganic mixed fertilizer plant–1), and (7) T6 (4 kg biochar + 1.1 kg organic-inorganic mixed fertilizer plant–1). The soil microbial communities were characterized using high-throughput sequencing of 16S and internal transcribed spacer (ITS) ribosomal RNA gene amplicons. The results showed that biochar combined with organic-organic fertilizer significantly improved soil properties (pH, alkali hydrolysable nitrogen, available phosphorus, available potassium, and available magnesium) and soil enzymatic activities [urease, dehydrogenase (DHO), invertase and nitrate reductase (NR) activities]. Furthermore, soil bacterial relative abundance was higher in biochar and organic-inorganic treatments as compared to control plots and the most abundant phyla were Acidobacteria (40%), Proteobacteria (21%), Chloroflexi (17%), Planctomycetes (8%), Bacteroidetes (4%), Verrucomicrobia (2%), and Gemmatimonadetes (1%) among others. Among the treatments, Acidothermus, Acidibacter, Candidatus Solibacter and F473 bacterial genera were highest in combined biochar and organic-inorganic treatments. The lowest bacterial abundance and bacterial compositions were recorded in control plots. The correlation analysis showed that soil attributes, including soil enzymes, were positively correlated with Chloroflexi, Planctomycetes, verrucomicrobia, GAL15 and WPS-2 bacterial abundance. This study demonstrated that biochar with organic-inorganic fertilizer improves soil nutrients, enzymatic activities and bacterial abundance.

Long-Term Organic-Inorganic Fertilization Regimes Alter Bacterial and Fungal Communities and Rice Yields in Paddy Soil.

Microorganisms are the most abundant and diverse organisms in soils and have important effects on soil fertility. In this study, effects of the long-term fertilization treatments no fertilizer (CK), chemical fertilizer (nitrogen–phosphorus–potassium (NPK)), and organic–inorganic fertilizer (NPK and organic fertilizer (NPKM)) on rice yield and soil bacterial and fungal community diversity, structure, composition, and interaction networks were evaluated. Of the three treatments, the highest rice yield was in NPKM. Bacterial richness was significantly higher in NPKM than in NPK. Fertilization treatment significantly altered β diversity of communities, species composition of bacterial and fungal communities, and structure of soil microbial networks. The most complex bacterial and fungal interaction co-occurrence network with the highest average degree and numbers of edges and nodes was in NPKM. Relative abundance of the plant growth-promoting fungus Trichoderma increased significantly in NPKM compared with CK and NPK. The results of the study indicate that bacterial richness and microbial community member interactions (network complexity) might be suitable indicators of soil biological fertility. This research provides new insights on the effects of different fertilization regimes on responses of soil bacterial and fungal communities and their contributions to crop yield. New indicators such as bacterial richness and complexity of microbial interaction networks are also identified that can be used to evaluate soil biological fertility.

Macroaggregation is promoted more effectively by organic than inorganic fertilizers in farmland ecosystems of China—A meta-analysis

Fertilizers can affect formation, size distribution and stability of soil aggregates in agricultural ecosystems. Although many independent studies have been recently carried out to understand the effects of fertilizers on soil aggregates in farmland ecosystems of China, the results remain widely contradictory. A meta-analysis was conducted using a total number of 1286 observations from 100 publications between 2005 and 2020 to quantitatively analyze the effects of different fertilizer treatments, duration of fertilizer application, regional heterogeneity, soil texture, and aeration conditions on the composition of soil aggregates. Results showed that long-term annual single application of organic fertilizer, inorganic fertilizer (N and NPK) and combined application of organic and inorganic fertilizers increased the proportion of > 2 mm fractions, but decreased the proportion of 0.25–0.053 mm and < 0.053 mm fractions, respectively. The promotion of macroaggregates (> 0.25 mm) by long-term application of organic fertilizer and the combined application of organic and inorganic fertilizers were significantly stronger than inorganic fertilizer, but the opposite for microaggregate (< 0.25 mm). The application of organic and inorganic fertilizer and straw return should be applied in sandy loam and silty loam, and clay loam was applied mainly manure (M), nitrogen plus manure (NM), nitrogen, phosphorus and potassium plus manure (NPKM) and nitrogen, phosphorus and potassium plus straw return (NPKS), while reducing the single application of inorganic nitrogen (N). Inorganic fertilizers and combined with organic-inorganic fertilizer increased the proportion of > 2 mm fractions in anaerobic soil significantly more than that in well-aerated soil. Long-term annual single application of N and M promoted the proportion of > 2 mm and 2–0.25 mm fractions significantly more than that of combined application of nitrogen and phosphorus and potassium (NPK), NM, NPKM and NPKS in experiments conducted in the Northeast of China. In addition, our results also showed that the proportion of macroaggregates did not increase linearly with continuous fertilizer input, but with the extension of fertilization durations, the macroaggregates transformed to microaggregates gradually after reaching the saturation state. Organic fertilizer and organic-inorganic combined application had longer time to promote macroaggregates than inorganic fertilizer.

The Thresholds and Management of Irrigation and Fertilization Earning Yields and Water Use Efficiency in Maize, Wheat, and Rice in China: A Meta-Analysis (1990–2020)

The increases in crop yield in China are linked to massive increases in fertilizer and water input, which have also accelerated the degradation of soil and environmental pollution. Nevertheless, the long-term changes in crop yield and water use efficiency (WUE) of three major cereals (maize, wheat and rice) in response to field management practices are rarely reported. This meta-analysis evaluated the effect of field management (nitrogen input (N), irrigation, fertilizer type, fertilization frequency, and irrigation method) on crop yield and WUE between 1990 and 2020 based on 3152 observations. We found that the N thresholds for maize, wheat, and rice were 150–200 kg ha−1, 140–210 kg ha−1, and 90–135 kg ha−1, respectively. N fertilization within the threshold levels increased the crop yield and WUE of maize (84% and 74%), wheat (47% and 41%), and rice (55% and 30%). The irrigation (mm) thresholds for maize and wheat were 180–240 mm and 300–400 mm and crop yield and WUE were increased by 37% and 13% for maize and by 84% and 41% for wheat. Agricultural management increased yield and WUE (% and %) through drip irrigation (23 and 13 maize; 31 and 14 wheat), alternate wetting and drying (AWD) (26 and 30 rice), split fertilization (31 and 21 maize; 64 and 40 wheat; 33 and 25 rice) and organic–inorganic fertilizer (43 and 39 maize; 68 and 66 wheat; 38 and 34 rice). With the increase in HI (humidity index) from 10 to 30, the contribution of irrigation to WUE decreased, but that of fertilization increased. This study concludes that N fertilizer and irrigation applications between threshold levels along with suitable field management is a win–win strategy to achieve climate-smart agricultural production with minimum damages to soil and environment and at lower dependence on fertilizer and irrigation.

Complementarity in Rubber-Salacca Intercropping System under Integrated Fertilization Mixed with Organic Soil Amendments

The replanting practice of rubber monocropping in Southern Thailand has depleted soil fertility. Most rubber planted areas in the region were under intensive chemical fertilization resulting in less soil organic matters and root proliferation. With the instability of rubber prices, some rubber farmers converted from monocropping into intercropping. Integrated fertilization in which mixed organic-inorganic fertilizers are combined with organic soil amendments could be considered in a rubber-based intercropping system to increase land productivity with cost-saving fertilization by rehabilitating soil properties. A study was conducted at a rubber-salacca intercropping farm comprised of 14-year-old mature rubber trees associated with eight-year-old salacca palms to identify the consequences of the integrated fertilization combined with two organic soil amendments: humic acid (HSA); chitosan (CSA). Changes in soil organic matter (SOM), leaf area index (LAI), fine root traits, tree physiological status, and crop productions under the two integrated fertilization were compared against the controlled application of conventional chemical fertilizer. The CSA application increased the SOM in the topsoil layer by 80%. In the 21 – 40 cm soil depth, the rubber roots treated with HSA and the salacca palm roots treated with CSA showed greater fine root length density (FRLD). Under CSA, the physiological status of the rubber trees showed less stress. The treatments of HSA and CSA showed 145% and 72%, respectively, higher in total production of salacca palm than that of the chemical fertilization. Improvements in the soil fertility, the root’s function, the crops’ yields, and the tree physiological status were consequences as complementarity in the system under the integrated fertilizations.

Improved tomato yield and quality by altering soil physicochemical properties and nitrification processes in the combined use of organic-inorganic fertilizers

Fertilization is an effective measure to improve crop yield and quality. The combined use of cow manures and inorganic fertilizers is a suggested fertilization method to achieve high tomato yield and maintain soil fertility, but its impacts on soil physicochemical properties and microbial nitrification process in tomato rhizosphere are still unclear. In this study, cherry tomato was cultivated with different fertilizers to explore the relationships between rhizosphere soil physicochemical variables, nitrification process and tomato quality. Our work found that the optimal organic-inorganic fertilizer treatment was 25% cow manure and 75% inorganic fertilizer, which significantly increased tomato yield by 245% (2.35 ± 0.22 kg·pot−1), and enhanced vitamin C, lycopene, total soluble solids concentration, total soluble sugar concentration, sugar-acid ratio by 11.6%, 75.2%, 9.2%, 9.4% and 96.7%, respectively. Application of 100% cow manure significantly increased soil pH, nitrogen and carbon from the full fruiting period to the end-fruiting period, but did not achieve good tomato quality and yield. 100% inorganic fertilizer application could increase tomato yield by 72.9% (1.17 ± 0.31 kg·pot−1), but the soil quality was remarkably degraded. Similar evidence was found from soil microbial biomass carbon/nitrogen (MBC/MBN) and enzyme activities. Application of cow manure changed soil ammonia oxidizing bacterial communities, increasing Nitrosovibrio and Nitrosomonas but decreasing Nitrosospira. These results suggested that the combined use of 25% cow manure and 75% inorganic fertilizer was the best condition for tomato production, explained by a balanced soil physicochemical variables and microbial nitrification process. Our findings offered suggestions to reasonably optimize fertilization strategies.

Effect of high soil C/N ratio and nitrogen limitation caused by the long-term combined organic-inorganic fertilization on the soil microbial community structure and its dominated SOC decomposition

The application of organic fertilizers, such as straw and manure, is an efficient approach to maintain soil productivity. However, the effect of these organic fertilizers on soil microbial nutrient balance has not yet been established. In this study, the effects of the long-term combined organic-inorganic fertilization on microbial community were investigated by conducting a 30-year-long field test. Overall, the following five fertilizer groups were employed: inorganic NP fertilizer (NP), inorganic NK fertilizer (NK), inorganic NPK fertilizer (NPK), NPK + manure (MNPK), and NPK + straw (SNPK). The results indicated that the mean natural logarithm of the soil C:N:P acquisition enzyme ratio was 1.04:1.11:1.00 under organic-inorganic treatments, which showed a deviation from its overall mean ratio of 1:1:1. This indicates that microbial resources do not have a balance. Vector analysis (vector angle <45°) and threshold elemental ratio analysis (RC:N-TERC:N > 0) further demonstrated that the microbial metabolism was limited by Nitrogen (N) under SNPK and MNPK treatments. N limitation further influenced soil microbial community structure and its dominated SOC decomposition. Specifically, Microbial communities transformed into a more oligotrophic-dominant condition (fungal, Acidobacteria, Chloroflexi) from copiotrophic-dominant (Proteobacteria, Actinobacteria) condition with increasing N limitation. Lysobacter genus and Blastocatellaceae family, in the bacterial communities along with the Mortierella elongata species in fungal communities, were markedly associated with the N limitation, which could be the critical biomarker that represented N limitation. Both correlation analysis and partial least squares path modeling showed significant positive effects of N limitation on the ratio of bacterial functional genes (Cellulase/Amylase), involved in recalcitrant SOC degradation.

Effects of vertical rotary subsoiling with combined organic and inorganic fertilization on water use efficiency and yield of forage maize in a semi-arid area.

Both reasonable soil tillage and fertilization management play critical roles in improving the yield and water use efficiency (WUE) of forage maize in the semi-arid area of Loess Plateau. A field experiment was conducted at Dingxi experimental station of Gansu Academy of Agricultural Sciences between 2017 and 2019. We explored the effects of tillage method and fertilization type on yields and WUE of forage maize, as well as the economic benefits. There were four treatments in the experiment, including traditional rotary tillage + organic-inorganic fertilization (TOF), deep rotary tillage + organic-inorganic fertilization (DOF), and vertical rotary subsoiling + organic-inorganic fertilization (VROF), and the traditional rotary tillage + inorganic fertilization as the control (TF). Our results showed that, compared with DOF, TOF, TF, and VROF all decreased soil water storage in 0-300 cm soil layer at flowering stage, ranging from 16.9 mm to 79.9 mm, but they all increased soil water consumption by 9.7-22.4 mm during vegetative growing stages, 11.0-19.8 mm during reproductive stage in the dry years. Due to significant improvement in water absorption, VROF increased dry matter weight at maturity by 3.9%-13.4% compared to other treatments. Similarly, plant height, ear length, grain number per ear, 100-grain weight, and double ear rate under VROF were significantly increased, while bald head length was decreased significantly, when compared with other treatments. As a result, over the three experimental seasons, VROF increased the grain and biological yield by 4.3%-51.5% and 4.3%-25.7% compared to other treatments, respectively. Accordingly, WUE calculated by grain and biomass yields were increased by 2.7%-36.9% and 3.6%-13.5% under VROF, compared to other treatments. VROF increased the unit gross total output value and the net income by 5.1%-32.9% and 6.9%-80.5% respectively, compared to other treatments. These results demonstrated that VROF is a drought-resistant and yield-increasing farming technology for sustainable forage maize production in the semi-arid area of the Loess Plateau, Northwest China.

Active carbon pool-size is enhanced by long-term manure application

We studied the dynamics of soil organic carbon (SOC)-pool mineralisation in agricultural soil. A laboratory incubation experiment was conducted using the soil from a long-term experiment involving the following fertilisation regimes: no fertilisation (CK); mineral (NPK); organic (M), and combined organic-inorganic fertilisers (MNPK). SOC mineralisation rate decreased as follows: MNPK &amp;gt; M &amp;gt; NPK &amp;gt; CK. Cumulative SOC mineralisation (C&lt;sub&gt;m&lt;/sub&gt;) ranged between 730.15 and 3 022.09 mg/kg in CK and MNPK, respectively; 8.81% (CK) to 20.45% (MNPK) of initial SOC was mineralised after a 360-day incubation. Soil C&lt;sub&gt;m&lt;/sub&gt; values were significantly higher under NPK, M, and MNPK compared to those under the CK treatment. Dynamic variation in C&lt;sub&gt;m&lt;/sub&gt; with incubation time fitted a double exponential model. Active carbon pools accounted for 2.06–6.51% of total SOC and the average mean resistant time (MRT&lt;sub&gt;1&lt;/sub&gt;) was 28.76 days, whereas slow carbon pools accounted for 93.49–97.94% of SOC, with an average MRT&lt;sub&gt;2&lt;/sub&gt; of 8.53 years. The active carbon pool in fertilised soils was larger than in CK; furthermore, it was larger in M- and MNPK- than under NPK-treated plots. SOC decomposed more easily in long-term fertilised plots than in non-fertilised plots.

Enhancing phosphorus availability, soil organic carbon, maize productivity and farm profitability through biochar and organic–inorganic fertilizers in an irrigated maize agroecosystem under semi‐arid climate

AbstractBiochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha‒1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.