Rate Of Chemical Fertilizer Research Articles

Lowering Chemical Fertilizers Rate in ‘Black Amber’ Plum Orchard for Improving Sustainable Resource Management: Effect on Soil Health and Fruit Quality

ABSTRACT The combined application of chemical fertilizers and organic material is a transitional approach toward more sustainable and productive farming. This study aimed to investigate the response of low chemical fertilizer rates and supplementing with organic materials on soil health and fruit quality. In plum orchard, combination of reduced chemical fertilizer rates (R80; R70; R60) with organic manures (F; V) at varying levels based the loss in nitrogen requirement and microbial inoculants (Bf; J) were studied over the conventional approach (R100) on soil health and fruit quality in a 2-year experiment. Soil analysis showed soil physico-chemical properties and enzymes activity with application of R70+V10+Bf. Compared to integrated treatments R100 saw highest availability of soil potassium and calcium. Application of R70+V10+J resulted in maximum improvement in fruit weight, TSS and soluble sugar content. Fruit set percentage was higher in treatment R70+V10+Bf. Fruit yield showed significant changes with treatments R70+V10+Bf and R70+V10+J having similar yield to R100. Our results suggest that by reducing the amount of chemical fertilizer by 30% and partially replacing it with organic materials had a positive effect on soil health without affecting the fruit production and quality.

Reduction in Chemical Fertilizer Rates by Applying Bio-Organic Fertilizer for Optimization Yield and Quality of Hemerocallis citrina Baroni

Reduction in Chemical Fertilizer Rates by Applying Bio-Organic Fertilizer for Optimization Yield and Quality of Hemerocallis citrina Baroni

Active Soil Organic Carbon Pools Decrease with Increased Time since Land-Use Transition from Rice Paddy Cultivation to Areca Nut Plantations under the Long-Term Application of Inorganic Fertilizer

Many croplands in the tropics of China have been converted over the last decades into areca nut plantations due to their high economic returns. This land-use transition was accompanied by changes in agricultural practices such as soil moisture regimes and fertilizer inputs, which may affect soil organic carbon (SOC) and its fractions, especially in tropical soils with low fertility and high nitrogen loss. Yet, how the time since land-use transition from rice paddy cultivation to areca nut plantations affects soil carbon dynamics and their underlying mechanisms in the tropics of China remains elusive. Here, areca nut plantation soils with different ages (2, 5, 10, 14, and 17 years) and paddy fields in the tropical region of China were investigated. The study result indicates that the contents of dissolved organic carbon (DOC), particulate organic carbon (POC), easily oxidized organic carbon (EOC), light organic carbon (LFOC), and microbial biomass carbon (MBC) decreased significantly with increased time since land-use transition from rice paddy cultivation to areca nut plantations. Similarly, the ratios of DOC/SOC, MBC/SOC, POC/SOC, LFOC/SOC, and EOC/SOC decreased significantly with increased time since land-use transition. Compared with the paddy soil, the carbon pool management index decreased by 36.6–76.7% under the areca nut plantations, concluding that increasing the time since land-use transition from rice paddy cultivation to areca nut plantations with high application rates of chemical fertilizers resulted in reduced soil active carbon fractions and SOC supply capacity. Therefore, agricultural practices such as the use of organic fertilizers should be applied to improve the soil’s ability to supply organic carbon in managed plantation ecosystems in the tropics of China.

Microalgae-based biofertilizer improves fruit yield and controls greenhouse gas emissions in a hawthorn orchard.

Raising attentions have focused on how to alleviate greenhouse gas (GHG) emissions from orchard system while simultaneously increase fruit production. Microalgae-based biofertilizer represents a promising resource for improving soil fertility and higher productivity. However, the effects of microalgae application more especially live microalgae on GHG emissions are understudied. In this study, fruit yield and quality, GHG emissions, as well as soil organic carbon and nitrogen fractions were examined in a hawthorn orchard, under the effects of live microalgae-based biofertilizer applied at three doses and two modes. Compared with conventional fertilization, microalgae improved hawthorn yield by 15.7%-29.6% with a maximal increment at medium dose by root application, and significantly increased soluble and reducing sugars contents at high dose. While microalgae did not increase GHG emissions except for nitrous oxide at high dose by root application, instead it significantly increased methane uptake by 1.5-2.3 times in root application. In addition, microalgae showed an increasing trend in soil organic carbon content, and significantly increased the contents of soil dissolved organic carbon and microbial biomass carbon, as well as soil ammonium nitrogen and dissolved organic nitrogen at medium dose with root application. Overall, the results indicated that the live microalgae could be used as a green biofertilizer for improving fruit yield without increasing GHG emissions intensity and the comprehensive greenhouse effect, in particular at medium dose with root application. We presume that if lowering chemical fertilizer rates, application of the live microalgae-based biofertilizer may help to reduce nitrous oxide emissions without compromising fruit yield and quality.

Potassium resources management systems in Chinese agriculture: Yield gaps and environmental costs

China is the world's largest consumer of chemical fertilizers, with a strong reliance on imports of mineral K fertilizer up to 50 %. Inexpensive and renewable straw-K recycling is crucial for enhancing soil K fertility and carbon (C) sequestration. Here, national management networks for inorganic- and straw-K were systematically integrated to identify yield gaps and C mitigation potential in Chinese typical crop rotation systems. National spatio-temporal changes in soil K fertility in the past 40 years were also mapped, indicating that about 52 % of national cereal arable cropland was still under low-K status in 2020. Compared with the inorganic K system (INK), grain yields of maize, wheat, and rice were respectively reduced by 9.4 %, 14.9 %, and 13.4 % under 0 K system, and increased by 5.2 %, 6.2 %, and 3.0 % under straw-based K recycling system (SBK system). Estimated net C emissions with the SBK system were 11.6 % (maize) and 47.4 % (wheat) lower than with the INK system, mainly due to the larger increase in soil C sequestration than in N2O production. Conversely, the SBK system increased net C emissions in rice by 57.6 % than the INK system due to larger increase in CH4 emissions. Scenario analyses showed that the annual C mitigation potential in the SBK system would approach 16.9 % (spring maize), 46.4 % (wheat-maize), 62.9 % (rice-wheat), and 22.4 % (rice-rice) by optimising the annual chemical fertilizer rate and seasonal straw distribution. Integrated inorganic- and straw-K management could also be extended to other K-limited developing and less-developed regions to enhance global food security and agricultural green development.

Effect of Long-term Application of Organic, Inorganic and Integrated Nutrients on Soil Potassium Fractions in a Vertisol of Central India

The present study was conducted at the experimental field of College of Agriculture, Indore during 2018-2019.Soybean (cv. JS-9305), was grown with 80 kg ha-1 seed rate with row to row and plant to plant spacing of 40 cm X 5 cm. Soybean crop was grown as per standard cultural practices. The experiment was conducted with nine treatments viz., T1- unfertilized control, T2- 20 kg N + 13 kg P ha-1, T3- 30 kg N + 20 kg P ha-1, T4- 40 kg N + 26 kg P ha-1, T5- 60 kg N + 35 kg P ha-1, T6- 6 t ha-1 FYM + 20 kg N + 13 kg P, T7- 5 t ha-1 crop residues + 20 kg N + 13 kg P, T8- 6 t ha-1 FYM and T9- 5 t ha-1 crop residues (CR) laid out in a randomized block design (RBD) having three replications. Different K fractions in soil sample viz., water soluble-K, available-K, exchangeable-K, non-exchangeable-K, lattice-K and total-K were determined following standard methods. The mean values were grouped for comparisons and the least significant differences among them were calculated at p<0.05 confidence level using ANOVA statistics. The results of present study revealed that to sustain K status in Vertisol there is a need of K application along with organic manure/crop residue. The application of organics with and without N and P application can sustain the Lattice-K availability in long run under soybean based cropping system of Vertisols. The rate of chemical fertilizer can be reduced up to 50% due to long term application of 6 t ha-1 FYM or 5 t ha-1 crop residues are added to soil.

Combined application of organic manure and reduced-rate chemical fertilizer improved growth, nutrient use efficiency, biomass accumulation, and carbon sequestration of Zanthoxylum armatum seedlings

The possibility of incorporating organic manure (OM) to reduced rates of chemical fertilizers to augment biomass production and carbon sequestration (Cseq) and the role of nitrogen (N), phosphorus (P), and potassium (K) uptake in vegetation Cseq were investigated through pot experiment with 1-year-old Zanthoxylum armatum seedlings. Seven treatments were designed, including NPK, PK, NP, NK, OM, MNPK (50% NPK + 50% OM), and control (CK, no fertilization). MNPK application improved nutrient uptake of 2.76-fold N, 3.34-fold P, and 2.01-fold K, resulting in the highest biomass production and biomass Cseq (1.65-fold) as compared to CK. Correlation and redundancy analysis revealed that Cseq is significantly associated with biomass production ( r = 0.994) and regulated by N and P uptake. The highest nutrient use efficiency was recorded for N (38.8%), followed by K (21.1%) and P (16.4%) under MNPK application. Therefore, MNPK could be an optimum measure regarding fertilizer saving, biomass production, and attaining C neutrality.

Nanofertilizers as an alternative to inorganic fertilizers: A review

The population of the world is steadily increasing, in contrast to the natural resources which are limited and subjected to further depletion. This induces pressures to develop effective agricultural production systems to meet the growing demands on food and, thus, to mitigate hunger and poverty worldwide. Generally, inorganic fertilizers play a crucial role in maintaining soil fertility and improving crop yield and quality. Inorganic chemical fertilizers are regarded as the main source to supply crops with their needs of nutrients. Proper nutrient management of crops is a major challenge worldwide as it relies predominantly on chemical fertilizers. However, inorganic fertilizers are not only costly but may be harmful and pose risks to human health and have negative impacts on the environment. About half of the amount of applied fertilizers is used by the crop, whereas the remaining fertilizers are lost through leaching and gaseous emissions. The lost nutrients contribute to environmental pollution, global warming and climate change. Moreover, high application rates of chemical fertilizers can deteriorate soil fertility and raise soil salinity and thus lower crop production and quality will occur. This creates a need to invent smart fertilizers that are friendly to the environment, particularly those of high nutrient use efficiency and low leaching potential. Nanotechnology has a vital role in the construction of such fertilizers (nanofertlizers). In these fertilizers, nutrients are bound to nano-dimensional adsorbents (nanomaterials), which release nutrients very slowly as compared to conventional chemical fertilizers. Nanofertilizers are nutrients coated or encapsulated with different types of nanomaterials. They have unique properties like large surface area, slow-release profile, and controlled delivery of nutrients to the targeted sites to meet the nutrient requirements of crops. Nanofertilizers are emerging as a promising alternative to conventional chemical fertilizers, as they offer great opportunities to improve plant nutrition under harsh environments. The benefits associated with the use of nanofertlizers are opening new approaches toward the development of sustainable agriculture. However, further studies are needed for a sound and safe application of nanofertlizers. In this review, researchers’ attempts to produce and use nanofertlizers for sustainable crop production have been presented. The advantages and limitations of the application of these smart fertilizers have also been discussed. Key words: Nanoparticles, Sustainable agriculture, Phytotoxicity, Slow and controlled release, Metal oxides

Comparison of comprehensive performance of kiwifruit production in China, Iran, and Italy based on emergy and carbon emissions

Extensive kiwifruit farming patterns worldwide are generating increasing environmental stress and thus hindering their sustainability. Comprehensive performance, based on resource efficiency and resource structure, pollutant emissions’ impact and carbon emission, is still not clear for this planting system. Therefore, this study proposes a comprehensive evaluation of kiwifruit planting systems by combining emergy analysis with carbon emission accounting method. The proposed approach not only considers the resource efficiency and resource structure of this planting system, as well as its carbon emission intensity, but also describe tradeoffs among emergy sustainability, pollutant emissions’ impacts and carbon emission intensity using the proposed index - Co-benefit index (CBI). Finally, four kiwifruit planting systems from China (Kiwifruit planting system in Sichuan province (SCPS) and Kiwifruit planting system in Shaanxi (SXPS)), Italy (Kiwifruit planting system in Italy (ITPS)) and Iran (Kiwifruit planting system in Iran (IRPS)), as case studies, are investigated using the presented approach. The study results show that (1) carbon emission intensity (CO2-eq/kg product) embodies trends of SXPS (0.16) > ITPS (0.15) > SCPS (0.12) > IRPS (0.11); (2) pollutant emissions’ impact intensity follows the trends of SXPS (2.54E+14) > ITPS (1.58E+14) > SCPS (8.29E+13) > IRPS (2.56E+13) in units of sej/t product; (3) environmental sustainability reveals trends of IRPS > ITPS > SXPS > SCPS mainly due to different environmental load rates. Generally, the four systems are not sustainable in the long term due to their high dependence on nonrenewable resources (especially labor and services (L&S) and chemical fertilizers); (4) results of Co-benefit index reflect the trends of IRPS > SCPS > ITPS > SXPS accordingly. Some targeted measures are proposed for SCPS, SXPS and ITPS. Considering low sustainability level, it is urgent for the four kiwifruit planting systems to further improve their utilization rate of chemical fertilizer and resource structure in the future.

Morphological and Physiological Response of Tomato to Sole and Combined Application of Vermicompost and Chemical Fertilizers

Chemical fertilizers are commonly used to meet the nutritional demands of crops and boost their yields. However, their high costs and excessive application in soils increase the cost of production and have negative effects on the soil and environmental health. Vermicompost is an organic amendment that can potentially lessen the dependence on chemical fertilizers, with the additional advantages of sustainable nutrient supply to crops and maintaining soil health. To evaluate the potential of the two diverse vermicompost, the sole and combined applications of these vermicompost with reduced rates of chemical fertilizers were used for tomato cultivation in a field study. The results indicated that vermicompost produced from cattle manure combined with chemical fertilizers was more effective in improving tomato growth, physiology, yield, and nutritional attributes. Compared to the control treatment (NP applied), the combined application of vermicompost and chemical fertilizer significantly improved the root length (21.6%), plant height (167%), SPAD value (13.5%), chlorophyll ‘a’ (96%), chlorophyll ‘b’ (161%), relative water content (16%), membrane stability index (18%), carotenoid (87%), yield (82%), photosynthetic rate (148%), fruit diameter (83%), protein (89%), fat (27.5%), fiber (12%), vitamin C (52%), calcium (54%), magnesium (117%), phosphorus (38%) and potassium (128%). In addition, significant improvements in different soil physicochemical properties were also pragmatic. The results suggest that vermicompost application with reduced doses of chemical fertilizers can be used to improve crop yield and soil physico-chemical properties.

Co-incorporation of Chinese milk vetch (Astragalus sinicus L.) and chemical fertilizers alters microbial functional genes supporting short-time scale positive nitrogen priming effects in paddy soils

Nitrogen (N) priming is a microbially mediated biochemical process as affected by different incorporation practices. However, little information is known about the microbial mechanisms driving the response of N priming to co-operation of Chinese milk vetch (CMV, Astragalus sinicus L.) and different rates of chemical fertilizers in paddy soils in South China. Here, an anaerobic incubation experiment was conducted to study N priming effects (PE) and their relationships with soil microbial functional genes after CMV incorporation alone (M), co-incorporation of CMV with 100% (normal dosage) chemical fertilizers (MC100), and co-incorporation of CMV with 80% chemical fertilizers (MC80). Co-incorporation of CMV and chemical fertilizers enhanced the short-time scale (the first 20 d of incubation) positive PE of N, while no significant differences existed among the three treatments on day 60 or 90 of incubation (P > 0.05). Compared with the M treatment, gross priming effect (GPE) in the MC100 and MC80 treatments significantly increased by 34.0% and 31.3%, respectively, and net priming effect (NPE) increased by 47.7% and 47.8%, respectively, during the first 20 d of incubation (P < 0.05). This was likely attributed to soil nutrient availability and added substrate quality. The MC100 and MC80 treatments increased the gdhA gene abundance by 5.0% and 9.8%, increased the gdh2 gene abundance by 12.7% and 45.7%, and increased the nasB gene abundance by 9.5% and 41.4%, respectively, in comparison with the M treatment on day 20 of incubation. Correlation analyses indicated that soil microbial functional genes involved in N mineralization (gdhA and gdh2), assimilatory nitrate reduction (nasB), and nitrification (amoB) were significantly correlated with N priming under different incorporation practices during the incubation period (P < 0.05). Thus, co-incorporation of CMV and chemical fertilizers can regulate soil microbial community functional gene structure, which may accelerate mineralization and assimilatory nitrate reduction and inhibit nitrification, thereby increasing the short-term positive PE of N in the present study.

Reduction in Nitrogen Rate and Improvement of Nitrogen Use Efficiency without Loss of Peanut Yield by Regional Mean Optimal Rate of Chemical Fertilizer Based on a Multi-Site Field Experiment in the North China Plain

It is important to quantify nutrient requirements and optimize fertilization to improve peanut yield and fertilizer use efficiency. In this study, a multi-site field trial was conducted from 2020 to 2021 in the North China Plain to estimate nitrogen (N), phosphorus (P), and potassium (K) uptake and requirements of peanuts, and to evaluate the effects of fertilization recommendations from the regional mean optimal rate (RMOR) on dry matter, pod yield, nutrient uptake, and fertilizer use efficiency. Results show that compared with farmer practice fertilization (FP), optimal fertilization (OPT) based on the RMOR increased peanut dry matter by 6.6% and pod yield by 10.9%. The average uptake rates of N, P, and K were 214.3, 23.3, and 78.4 kg/ha, respectively, with 76.0% N harvest index, 59.8% P harvest index, and 41.4% K harvest index. The OPT treatment increased N, P, and K uptake by 19.3%, 7.3%, and 11.0% compared with FP, respectively. However, the average of yield, nutrition uptake, and harvest indexes of N, P, and K were not significantly affected by fertilization. The peanut required 42.0 kg N, 4.6 kg P, and 15.3 kg K to produce 1000 kg of pods. The OPT treatment significantly improved the N partial factor productivity and N uptake efficiency but decreased the K partial factor productivity and K uptake efficiency. The present study demonstrates that fertilizer recommendations from RMOR improve N use efficiency, and reduce N and P fertilizer application without yield loss in regions with smallholder farmers, and the corresponding estimation of nutrient requirements helps to make peanut fertilization recommendations.

Effect of bio enriched FYM on growth, yield and economics of finger millet (Eleusine coracana (L.) Gaertn) under dryland condition

Crop suffers from the slow release of nutrients from organic manures at initial stages, which may cause a significant reduction in crop yield and farm income. This can be overcome by enrichment of organic manures with beneficial microbial culture and a judicious combination of inorganic fertilizers with such enriched organic manures. Finger millet was grown at AICRP for dryland Agriculture field during Kharif -2019 to study the effect of bio-enriched FYM viz., nitrogen fixers, phosphorus solubilizers, potassium solubilizers, PGPR and microbial consortia with 60 and 80 per cent RDF on growth, yield and economics of finger millet. Application of bio enriched FYM with microbial consortia + 80 per cent RDF (T10) recorded significantly higher plant height (86.38, 111.52 and 115.33 cm), number of tillers per plant (4.42, 5.20 and 5.42) and dry weight per plant (5.50, 15.05 and 27.27 g) at 60, 90 DAS and at harvest, respectively. Whereas, higher grain yield (2999 kg ha-1) and straw yield (4274 kg ha-1) were recorded in T10 treatment Which received 80 per cent RDF with microbial consortia and sème trématent recorded additional return of rupees 12683 per hectare over recommended use of fertilizers. The overall result showed that the bio enrichment of FYM with microbial consortia tended to reduce the application rate of chemical fertilizer and thus microbial consortia along with 80 per cent RDF could be recommended for finger millet.

Changes in the Microbial Structure of the Root Soil and the Yield of Chinese Baby Cabbage by Chemical Fertilizer Reduction with Bio-Organic Fertilizer Application.

Using high-throughput sequencing, this study aimed to explore the response of soil microbial community and Chinese baby cabbage yield to the reduction of chemical fertilizers combined with bio-organic fertilizer. Our experiments consisted of conventional fertilizer (CK), 30% chemical fertilizer reduction + 6,000 kg/ha bio-organic fertilizer (T1), 30% chemical fertilizer reduction + 9,000 kg/ha bio-organic fertilizer (T2), 40% chemical fertilizer reduction + 6,000 kg/ha bio-organic fertilizer (T3), and 40% chemical fertilizer reduction + 9,000 kg/ha bio-organic fertilizer (T4). Compared with CK, soil microbial diversity and richness were higher for all treatments with added bio-organic fertilizer. Principle coordinate analysis (PCoA) showed that the bacterial and fungal communities in T2 and T4 were similar to each other. Redundancy and Spearman's correlation analyses of microbial communities and soil physicochemical properties revealed that reductions in chemical fertilizer rate combined with bio-organic fertilizer had a stronger impact on the fungal than the bacterial community. They also increased the relative abundance of the dominant bacterial and fungal phyla. Chinese baby cabbage yield was relatively higher under the combined bio-organic fertilizer plus reduced chemical fertilizer rate with T2 showing the highest yield. Therefore, this approach is feasible for sustainable agricultural, cost-effective and profitable crop production. IMPORTANCE Chemical fertilizers are commonly used for agriculture, though bio-organic fertilizers may be more efficient. We found that a mixture of bio-organic and moderately reduced chemical fertilizer was more effective than chemical fertilizer alone, as it raised the Chinese baby cabbage yield. Further, the presence of bio-organic fertilizer enhanced overall soil physicochemistry, as well as improved the beneficial bacterial and fungal abundance and diversity. Thus, we found that fertilizer combination sustainably & cost-effectively improves crop & soil quality.

Changes in soil bacterial community and functions by substituting chemical fertilizer with biogas slurry in an apple orchard.

Growing concerns about the negative environmental effects of excessive chemical fertilizer input in fruit production have resulted in many attempts looking for adequate substitution. Biogas slurry as a representative organic fertilizer has the potential to replace chemical fertilizer for improvement of sustainability. However, it is still poorly known how biogas slurry applications may affect the composition of soil microbiome. Here, we investigated different substitution rates of chemical fertilizer with biogas slurry treatment (the control with no fertilizer and biogas slurry, CK; 100% chemical fertilizer, CF; biogas slurry replacing 50% of chemical fertilizer, CBS; and biogas slurry replacing 100% of chemical fertilizer, BS) in an apple orchard. Soil bacterial community and functional structure among treatments were determined using Illumina sequencing technology coupled with Functional Annotation of Prokaryotic Taxonomy (FAPROTAX) analysis. Leaf nutrient contents, apple fruit and soil parameters were used to assess plant and soil quality. Results showed that most of fruit parameters and soil properties were significantly varied in the four treatments. CBS treatment increased the contents of soil organic matter, alkali nitrogen and available potassium average by 49.8%, 40.7% and 27.9%, respectively. Treatments with biogas slurry application increased the single fruit weight, fresh weight, and dry weight of apple fruit average by 15.6%, 18.8% and 17.8, respectively. Soil bacterial community dominance and composition were significantly influenced by substituting of chemical fertilizer with biogas slurry. Biogas slurry application enhanced the relative abundance of some beneficial taxa (e.g. Acidobacteria Gp5 and Gp7, Parasegetibacter) and functional groups related to carbon and nitrogen cycling such as chemoheterotrophy, cellulolysis, and nitrogen fixation. Soil available phosphorus and potassium, pH and electrical conductivity were identified having a high potential for regulating soil bacterial specific taxa and functional groups. This study showed that the proper ratio application (50%: 50%) of biogas slurry with chemical fertilizer could regulate soil bacterial composition and functional structure via changes in soil nutrients. The variations of bacterial community could potentially take significant ecological roles in maintaining apple plant growth, soil fertility and functionality.

Spatial distribution of soil nutrients and evaluation of cultivated land in Xuwen county.

It is of great significance to promote the quantitative research of soil science and the implementation of precision agriculture. On this basis, taking Xuwen County as the research object, this paper comprehensively analyzed the soil characteristics of cultivated land in Xuwen County and clarify the soil nutrient content and spatial distribution characteristics of cultivated land in Xuwen County, this paper comprehensively applied the methods of geostatistics, geographic information system (GIS) and fuzzy mathematics, and referred to the cultivated land quality grade standard (GB/T 33469-2016), to analyze the soil characteristics and evaluate the soil fertility of this region. The results show that the optimal interpolation model of soil pH and available phosphorus (AP) is a Gaussian model, and the optimal interpolation model of soil organic matter (SOM), available nitrogen (AN) and available potassium (AK) is a J-Bessel model. In addition, the spatial correlation of AK is weak, whereas pH, SOM, AN and AP show moderate spatial correlation. The proportion of excellent, good, average, medium and poor comprehensive fertility index are 26.00%, 32.67%, 19.33%, 19.00% and 3.00%, respectively. The overall level of soil fertility in Xuwen County is above the average, and the fertility quality presents an obvious trend of high in the South and low in the North. Areas that above average fertility are mainly distributed in Maichen Town, Qujie Town, Nanshan Town and Chengbei Town. The results can provide theoretical basis for improving the utilization rate of chemical fertilizer, fine management of cultivated land and ecological environment in this region, which can help in decision-making of precision fertilization.

Long-Term Effects of Straw and Straw-Derived Biochar on Humic Substances and Aggregate-Associated Humic Substances in Brown Earth Soil

Turning maize straw into biochar is useful for improving soil fertility and mitigating climate change. However, the difference between straw and straw-derived biochar on soil aggregate associated humic substances has not been sufficiently studied in brown earth soil. The objective of this study was to investigate how different straw management practices affect soil humic substances and aggregate-associated humic substances in the field. As such, an eight-year study (2013–2020) was conducted on brown earth in Northeast China. Three treatments were applied: 1) CK, in which only chemical fertilizer was applied every year; 2) BC, in which biochar was applied at a rate of 2.625 t ha−1 (the same rate of chemical fertilizer as that in the CK was applied); 3) SR, in which straw was returned at a rate of 7.5 t ha−1 (the same rate of chemical fertilizer as that in the CK was applied). Both biochar and straw improved soil aggregate stability that reflected by the mean weight diameter (MWD) and geometric mean diameter (GMD). Compared to the CK treatment, the BC treatment enhanced humic carbon (HMC) both in bulk soil and different aggregate fractions. Biochar decreased the humic acid carbon (HAC) in bulk soil compared to the initial content, but no differences were observed between BC and CK after the eight-year field experiment. All of the aggregate-associated HAC contents were significantly enhanced in response to BC treatment. SR was an effective way to improve soil organic carbon (SOC) and humic substances in bulk soil and aggregate fractions. SR had a relatively small effect on the relative proportions of the C functional groups. Solid-state 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (CPMAS-NMR) spectra of bulk soils revealed that biochar increased the proportion of aromatic C. The ratios of alkyl C/O-alkyl C, aromatic C/aliphatic C, and hydrophobic C/hydrophilic C increased in response to the BC treatment compared to the other treatments. Taken together, biochar amendment can enhance soil aggregate stability, aggregate-associated HMC and stability of SOC on the scale of an eight-year field experiment. Biochar could be an effective approach to sequestrate carbon and improve the quality of brown earth soil.

Sustainable Plant Growth Promotion and Chemical Composition of Pyroligneous Acid When Applied with Biochar as a Soil Amendment.

The pyrolysis of biomass material results in pyroligneous acid (PA) and biochar, among other by-products. In agriculture, PA is recognized as an antimicrobial agent, bio-insecticide, and bio-herbicide due to antioxidant activity provided by a variety of constituent materials. Application of PA to crop plants and soil can result in growth promotion, improved soil health, and reduced reliance on polluting chemical crop inputs. More detailed information regarding chemical compound content within PA and identification of optimal chemical profiles for growth promotion in different crop species is essential for application to yield effective results. Additionally, biochar and PA are often applied in tandem for increased agricultural benefits, but little is known regarding the optimal proportion of each crop input. This work reports on the effect of combined applications of different proportions of PA (200- and 800-fold dilutions) and chemical fertilizer rates (100%, 75%, 50%, and 0%) in the presence or absence of biochar on Komatsuna (Brassica rapa var. perviridis, Japanese mustard spinach) plant growth. To elucidate the chemical composition of the applied PA, four different spectroscopic measurements of fluorescence excitation were utilized for analysis—excitation-emission matrix, ion chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry. It was determined that PA originating from pyrolysis of Japanese pine wood contained different classes of biostimulants (e.g., tryptophan, humic acid, and fulvic acid), and application to Komatsuna plants resulted in increased growth when applied alone, and in different combinations with the other two inputs. Additionally, application of biochar and PA at the higher dilution rate increased leaf accumulation of nutrients, calcium, and phosphorus. These effects reveal that PA and biochar are promising materials for sustainable crop production.

On the green and light-simplified and mechanized cultivation of cotton in a cotton-based double cropping system

<p id="C2">There are many prominent problems or challenges in the traditional cotton production under the cotton-based double cropping system, which include complex planting pattern and cumbersome cultivation technology, long growth period, low degree of mechanization, heavy inputs of labor, chemical fertilizers and pesticides, and the resulted low economic benefits. After nearly 10 years of researches and practice, China has established and applied the green and light-simplified and mechanized cultivation technology of cotton in a cotton-based double cropping system, namely the green production with reduced chemical fertilizers and pesticides, light and simplified field management, and mechanized production by using mechanics instead of labors. Based on the author's research and relevant research progress at home and abroad, this paper summarizes and reviews the basic concept, the technical route, the key technologies and theoretical basis of the green, light and mechanized cultivation of cotton under the cotton-based double cropping system. The core contents of the technology are one-time sowing by machinery (direct one seed precision sowing by machinery under no-tillage instead of cotton seedling transplanting, simultaneous sowing of seed and fertilizer, no thinning and no seedling replenishment), no pruning (avoid removal of vegetative branches and manual topping through close planting and chemical regulation to shape reasonable plant type and maturity), and one-time mechanical harvesting (establish a centralized fruiting population structure through comprehensive regulation and control) to save labor by 70%; Using cotton varieties with early maturity or mid-early maturity, reasonably higher plant density, one-off deep-soil application of controlled-release fertilizer and spraying fertilizer by UAV (Unmanned Aerial Vehicle) with water-soluble fertilizer for foliage, which can save fertilizer by 50%; and by making use of the resistance of insect-resistant cotton varieties, sowing late at an appropriate time to shorten cotton growth period, and control pests and diseases by using food or sex induced inducers, biological pesticides, insecticidal lamps, and UAV, which can save pesticide by 40%. Compared with traditional technologies, this technology has greatly reduced the labor inputs in cotton production, the substitution rate of agricultural machinery for labor has reached 60%, the utilization rate of chemical fertilizer has increased by more than 11.2%, and the economic benefit has increased by 30%. It also alleviates the non-point source pollution caused by excessive use of chemical fertilizer and pesticides, and provides technical support for promoting the fundamental reform of cotton production mode.

Effects of chemical fertilizer reduction combined with humic acid bio-fertilizer on soil biological properties and dry matter mass of maize.

A reduction of chemical fertilizers and improving fertilizer utilization rate are important for ensuring a balance between plant growth and minimizing the degradation of the black soil. We conducted a 2-year pot experiment with four treatments during 2019 and 2020, including T0: no fertilizer, T1: conventional use of chemical fertilizer, T2: 15% reduction of the chemical fertilizer combined with 400 kg·hm-2 of humic acid bio-fertilizer (HABF), and T3: 30% reduction of the chemical fertilizer combined with 600 kg·hm-2 of HABF, to examine the effect of reduction rates of chemical fertilizers combined with the HABF on soil microbial abundance, enzyme activity and nutrient content in maize cultivation. The results showed that the application of HABF significantly increased the abundance of soil bacteria and fungi, with the number of microbial colonies being positively correlated with the amount of HABF. When measured at the tassel stage of maize growth, T2 and T3 treatments significantly increased the activities of urease, sucrase, and catalase in soil by 11.4%-21.6%, 34.9%-46.7%, and 6.5%-13.4%, respectively. The available nitrogen contents in T2 and T3 treatments were higher than that in the T1 treatment by 8.2%-18.1%, which ensured the sufficient nitrogen supply to maize after the tassel stage. Soil available phosphorus and available potassium contents increased by 17.1%-121.0% and 9.6%-57.3%, respectively, compared with T1 treatment. With the increases of the amount of HABF, the activation effects of soil phosphorus and potassium and dry matter mass per plant increased significantly in T2 and T3 treatments compared with T1 treatment. In conclusion, HABF promoted the proliferation of soil bacteria and fungi, improved activities of catalase, urease, and sucrase, soil nutrient contents, and dry matter mass per plant. The 15% reduction of chemical fertilizer combined with 400 kg·hm-2 of HABF is the most suitable nutrient management strategy for maize production in black soil.