Mineral NPK Fertilizer Research Articles

Assessment of the Short-Term Fertilizer Potential of Mealworm Frass Using a Pot Experiment

The forecasted growth of insect production in the next few years will generate high quantities of frass (insect excreta). Although frass is increasingly considered a potential fertilizer, the dynamics of nutrient supply by frass is still poorly understood. Here, we aimed at gaining insight into the short-term fertilizer value of frass from mealworm (Tenebrio molitor L.) in order to optimize its sustainable use in agroecosystems. Using a short-term pot experiment, we showed that, even though frass has a great potential to be used as a substitute of mineral NPK fertilizer, its N fertilizer potential is mediated by its rate of application. At 10 t ha−1, due to its fast mineralization coupled with improvement in microbial activity (assessed using Biolog EcoPlate), frass was as effective as mineral fertilizer to supply N to plant. By contrast, at 5 t ha−1, the lower frass mineralization induced a reduced N uptake compared to its mineral control. Unlike N, frass was as effective as mineral fertilizer to supply P and K to plants irrespective of its application rate. This was attributed to the presence of P and K in a readily available form in frass. Taken together, our results indicate that mealworm frass supplies very rapidly N, P and K to plants but its effects on N dynamics should be better investigated to warrant its sustainable use as an alternative fertilizer for managing NPK nutrition in cropping systems.

Successive applications of fertilizers blended with biochar in the soil improve the availability of phosphorus and productivity of maize (Zea mays L.)

Potential shortages in the reserves of phosphorus (P) rock and low soil P availability are among the main limiting factors for agricultural development. Recent studies show that biochar plays a crucial role in regulating soil physicochemical properties and crop development. To further verify the contribution of biochar to availability of soil P and nutrient efficiency of crop P, a maize continuous cropping field trial was started in 2013 to investigate the effects of biochar (0 and 2.63 t ha−1) combined with P fertilizer (0 and 26 kg ha−1) on soil biologically-based P and maize P use efficiency and yield. The treatments included mineral NPK fertilizer (NPK), mineral NK fertilizer (NK), mineral NPK fertilizer in combination with biochar (NPK + BC) and mineral NK fertilizer in combination with biochar (NK + BC). The following results were obtained in 2017 and 2018: biochar increased the pH, electrical conductivity (EC), total C (TC) and total P (TP) of the soil. Biochar can increase soil biologically-based P (CaCl2-P, enzyme-P, citrate-P and HCl-P). The grain yield of the NPK + BC treatment reached the highest point and improved maize grain yield by 4.2 %–12.5 % compared with NPK fertilization alone. Moreover, the application of biochar (2.63 t ha−1) instead of phosphate fertilizer in these experimental conditions did not lead to a decrease in the yield of maize. The addition of biochar increased the contents and uptake of P in maize grains, while negatively affecting the content and uptake of P in maize stover. Increases in P fertilizer use efficiencies (PUE) (12.4 %–31.4 %) and agronomic P efficiencies (AEP) (21.6 %–51.2 %) occurred after the application of biochar. The yield of maize and PUE positively correlated with the soil biologically available P. The structural equation modeling (SEM) results suggest that the increases in maize yield could be ascribed to improvements in soil biologically-based P and soil properties. Therefore, the addition of biochar is an effective approach to enhance the yield of maize, which is not only relevant to the improvement of soil biologically-based P but also increases in P use efficiency.

Biowaste compost amendment modifies soil biogeochemical cycles and microbial community according to aggregate classes

The use of biowaste compost as soil organic amendment is of great interest for soil recovery. However, there is little knowledge of detailed effects on chemical, microbial, and biochemical properties in different soil compartments (aggregate classes) following long-term amendment with biowaste compost. We studied the distribution of soil organic carbon (SOC), total nitrogen (TN), soil microbial biomass (SMB), microbial community composition and activity in bulk soils and in three water stable aggregate classes (>250, 250–53, and <53 μm), after seven years of different fertilization treatments: biowaste compost (Com), mineral NPK fertilizers (Min), biowaste compost with half-dose N fertilizer (ComN), and no fertilizers as control (Cnt). Microbial biomass was assessed through a double-stranded DNA (dsDNA) based method and enzyme activities were determined using a microplate-based fluorometric assay. Denaturing gradient electrophoresis (DGGE) fingerprinting analysis was used to study the composition of both fungal and bacterial communities. Com and ComN treatments improved significantly SOC, TN and SMB in bulk soils and in all aggregate sizes. Composition of fungal and bacterial communities shifted with biowaste compost, more in soil aggregates than in bulk soils. To this change of microbial community composition in soil aggregates, corresponded a response of enzymes activities to fertilization treatments depending on aggregate size. Com treatment caused the highest enzyme activity in microaggregates (250–53 μm), whereas ComN and Min showed, in general, a higher activity in silt plus clay sized aggregates (<53 μm). The enzymes involved in biogeochemical cycle of P, with the exception of the phytase, displayed the lowest activity in macroaggregates (>250 μm), suggesting that the intensity of this cycle is lower in this soil niche; however, they increased with C accumulation due to both biowaste compost treatments. Furthermore, fungal diversity and richness decreased with fertilization treatments in all fraction except in macroaggregates. Thus, soil aggregates regulated the feedback of chemical, biochemical and microbial properties in response to soil fertilization strategies.

Sewage sludge biochars effects on corn response and nutrition and on soil properties in a 5-yr field experiment

Sewage sludge biochar (SSB) is the solid product obtained after the pyrolysis of sludge. In the last ten years, hundreds of studies have evaluated the effects of SSB as a soil amendment over a short period of time. Thus, doubts remain about the temporal behavior of SSB under field conditions. The objective of this study was to evaluate, under field conditions, the effects of SSB on the fertility indicators (pH, potential acidity, Mehlich1-P and -K, CEC and KCl-exchangeable Ca, Mg and Al) and corn yield in an Oxisol over five years. For this purpose, soils receiving biochar produced at 300 and 500°C (SSB300 and SSB500, respectively) and biochar in combination with mineral fertilization (SSB300 + NPK and SSB500 + NPK) were evaluated. Grain yield, soil pH, soil H + Al, and macronutrient contents (N, P, K, Ca, Mg and S) in soil and corn leaves were determined. Over five years, SSB increased total N and Mehlich1-P in the soil. Nevertheless, biochars were unable to raise soil pH and provide satisfactory amounts of K. The combination of SSB with mineral NPK fertilizer provided all the macronutrients required for corn and increased the leaf contents, especially for P, leading to an average 16% increase in grain yield in soils that received the treatment SSB300 + NPK. In general, pyrolysis temperature did not alter the parameters evaluated. SSB has the potential to provide nutrients to the soil, with a residual effect of at least three years, which can be enhanced by combined application with mineral NPK fertilizer.

Effect of Nitrogen, Phosphorus and Potassium Fertilizers as Nano and Regular Mineral on Maize Growth (Zea mays L.) Plants Grown in Saline-Sodic Soil, at North Sinai, Egypt

Field experiments were conducted to compare nano NPK fertilizers with ordinary mineral NPK fertilizers on maize (Zea mays L. Triple hybrid Giza 320) grown on a saline sodic sandy loam soil. Two experiments were conducted on 2018 and 2019 seasons at Romanh Village, North Sinai Egypt. The design was a randomized complete block, factorial (split plot). Factor1: Source (i.e. mineral ‘S1’ and nano ‘S2’). Factor2 Dose “rate” (i.e. kgha-1 NPK of 0/0/0, 120/180/60; 180/36/120 and 240/72/180 for D0, D1, D2 and D3 respectively. The fertilized treatments using the nano forms were much superior then those of the regular mineral ones. Superiority was up to the followings for each 8 and 12% for grain and straw yields respectively. For the other traits, superiorities for uptakes were up to 29% (straw N) 3% (grains N), 41% (straw P), 7 % (grain P), 27% (straw K) and 34% (grain K.). Fertilization enhanced plants to sustain salinity stress conditions. The mineral fertilization caused plants to accumulate more proline “g kg-1 fresh matter”: average of 44.3 for the mineral and 27.4 for the nano.

Growth Quality and Bioactive Compounds of Poplar Seedlings as Affected by Different Fertilization Treatments

Pot experiments were conducted during two successive seasons of 2019 and 2020 at the Fac. of Agric., Minia Univ. to investigate effects of four application rates of compost (0, 1, 2 and 3%) (w/w) and six treatments of bio-fertilizers and/or mineral NPK fertilization (control, Azotobacter chroococcum + Bacillus circulans, Azotobacter chroococcum + Bacillus megaterium, mixture of bio., mixture of bio. + 75% NPK and 100% NPK) on vegetative criteria, accumulation of bioactive compounds (phenolic compounds and flavonoids) through improving plant's secondary metabolism and antimicrobial activity of methanolic and ethanolic extracts of Populus alba. All compost treatments significantly improved all transplant vegetative growth parameters such as plant height, diameter, aerial part fresh and dry weights, main root length and roots fresh and dry weights, as well as, total chlorophylls and NPK% as compared to control. Biofertilizers and/or mineral NPK fertilization treatments significantly increased all the previous traits, the mixture of three species of bacteria plus 75% NPK followed by mineral full dose of NPK treatments were the most effective than other used treatments. The highest values were obtained when Populus alba transplants were grown in sandy soil contained 3% compost plus inoculation with three species of bacteria plus 75% NPK or compost at 3% plus 100 % NPK and these two treatments give the highest values of phenolic compounds in the methanolic and ethanolic extracts. This research confirmed that poplar is a promising wooden tree to be grown on sandy soils for timber production in Egypt, woody products and bioactive compounds.

POTENTIAL IMPACT OF THE IMPLEMENTATION OF THE NEW GREEN DEAL IN THE FIELD OF MINERAL FERTILIZATION ON THE YIELD OF MAIN AGRICULTURAL CROPS

The aim of the article is to estimate the impact of reducing the consumption of mineral fertilizers resulting from the New Green Deal assumptions on the yields of major crops in the 2030 perspective. The material for analysis was statistical data from the CSO and FAO. The collected data was processed dynamically by using trend analyzes and Pearson linear correlation. Maintaining the current trend of increasing the dose of NPK mineral fertilization will allow the use of crop production potential in Poland. On the other hand, the introduction of the NGD assumptions may result in a stagnation of crop yield at the current level. However, in relation to the scenario assuming the continuation of the current upward trend, these yields will be much lower. Reducing mineral fertilization introduced by means of an administrative decision without taking the principles of rational management of fertilizer components into consideration may have negative environmental consequences.

Towards Management of South Kivu Ferralsols by the Contribution of Different Types of Fertilizers: Their Influence on the Biofortified Climbing Bean Behaviour

For many tropical and subtropical countries, poor soil fertility management is still a major problem in agricultural production and requires sustained attention. This study was carried out to evaluate the effect of the combination of fertilizer types on the improvement of ferralsol properties and on biofortified climbing bean yield in South Kivu. The experimental field was conducted by using a CRB plot with three replications. Ten treatments were followed consisted of a control, mineral fertilizer NPK (150 kgha-1), farmyard manure (30 tha-1), liming (1.3 tha-1), fresh biomass of Tithonia diversifolia (30 tha-1), and their combinations. The results obtained show significant differences between the treatments and their ability to improve the chemical properties (acidity, OM, N, and K) of the ferralsol during the two cropping seasons. This improvement has led to improvements significantly in the growth, yield, and profitability of climbing beans. The combination of farm manure and NPK (2.6 tha-1); liming-NPK and straw biomass of Tithonia sp. presented the same yield performance. With a profit margin of 900 and 850 USDha-1, Tithonia sp. could replace expensive mineral fertilizers. This study shows that liming coupled with low rates of fertilizer or Tithonia sp. on ferralsol in eastern RD Congo conditions and have the potential for improving the availability of soil nutrients and providing the quantities required nutrients needed for growing biofortified climbing beans and thus reduce malnutrition in the region subsequently fight against Fe and Zn micronutrient deficiency.

Long-term partial replacement of mineral fertilizer with in situ crop residues ensures continued rice yields and soil fertility: A case study of a 27-year field experiment in subtropical China

High yields and environment-related issues because of over-fertilization in rice (Oryza sativa L.) production is a major concern in China. Partial replacement of mineral fertilizer (MF) with organic matter is considered a win–win approach for resource-saving and environmentally friendly rice production. Here, we examined the effects of reduced MF and in situ crop residue on the rice yield and soil fertility in the long term. A 27-year field experiment (a randomized block design with three replicates) in subtropical China was conducted to test the feasibility of the substitution in a double rice paddy ecosystem. The treatments were CT (no fertilizer application considered as control), NPK (mineral fertilizer N, P, and K), and RFC (reduced MF and in situ crop residue to supplement the reduced NPK dose). The crop residue included half of the rice straw and green manure contents, which were retained in situ in the RFC treatment. The RFC maintained the same rice yield and soil fertility levels as NPK. In general, soil organic carbon (SOC) and total nitrogen (TN) content in RFC increased by 10.3% –20.8%, and 7.5% –28.0%, respectively, than that in NPK from the 5th to the 25th years. There was no significant difference in the content and net accumulation of SOC, TN, and TP and soil available nutrients between the RFC and NPK treatments after 25 years. The average annual yields were 9690 and 9872 kg ha−1 for the NPK and RFC treatments, respectively. There was no difference in the yield of the first, second, and annual rice crops between RFC and NPK in most years (six of the fifty-four seasons showed a significant difference). RFC increased the partial factor productivity (PFP), agronomic efficiency (AE) of MF, and yield stability (CV) (p < 0.05). Positive nutrient balance and a reduced loss of nutrients are evident reasons for achieving better indicators (PFP, AE, and CV) for nutrient compensation and organic nutrient utilization in the RFC treatment. The partial replacement of MF with in situ crop residue retention, is a simple and efficient way to maintain the soil fertility and rice yield as NPK in southern China.

Effect of a &lt;em&gt;Pseudomonas fluorescens&lt;/em&gt;-based Biofertilizer on Sweet Potato Yield Components

A field experiment was conducted to study the effect of a Pseudomonas fluorescens-based biofertilizer on sweet potato (Ipomoea batatas (L) Lam) yield. The application was by immersion of cuttings before sowing for 0, 5, 10 and 15 minutes with combination doses of 0, 50 and 100% of NPK mineral fertilizer in a randomized block design with three replications (12 treatments-combinations). During the harvest (130 days after planting), some measurements related to yield components were recorded on ten randomly selected plants from each plot. All treatments with Pseudomonas’ immersion showed a positive productive response. With 100% NPK and the immersion in the biofertilizer for 15 min showed the highest yield (56.09 tha-1), followed by the other treatments with 100% NPK and without statistical differences among them. The treatment with 50% NPK and the immersion in Pseudomonas for 15 min (49.58 tha-1) had no statistical differences with the control variant (100% NPK, 51.60 tha-1). Based on the results, it can be concluded that this biofertilizer could be an appropriate alternative to increase the sweet potato yield, saving the 50% of the current quantity of the recommended mineral fertilizer, through a more friendly environmental techniques to promote a sustainable, efficient and productive agriculture.

Arbuscular mycorrhizal fungal communities of topsoil and subsoil of an annual maize-wheat rotation after 15-years of differential mineral and organic fertilization

Arbuscular mycorrhizal fungi (AMF) could improve crop yield by nutrient uptake from soil. However, how AMF of topsoil and subsoil respond to long-term differential application of mineral and organic fertilizers and how they are influenced in presence of different crops and growth stages have never been assessed together. Next generation sequencing was applied to profile soil AMF communities in both topsoil and subsoil from a typical arable soil (Eutric Regosol) in the Sichuan Base, southwest China. Soils were collected at anthesis and harvest of winter wheat and maize after 15-years of differential fertilization of an annual maize-wheat rotation (same inputs of nitrogen, N; but different in carbon, C; phosphorus, P; and potassium, K): (i) no-fertilization control (CT), (ii) 100% mineral NPK fertilizer (NPK), (iii) 60% mineral N and 100% mineral PK plus 40% N as crop residues (NPKCR); and (iv) 60% mineral N and 100% mineral PK plus 40% N as pig (organic) manure (NPKOM). Compared to CT, AMF diversity significantly decreased in topsoil, but increased in subsoil for both wheat and maize under NPK, NPKCR and NPKOM. The AMF community composition differed between NPK and CT in both topsoil and subsoil of maize and wheat. Both distance-based redundancy analysis (db-RDA) and structural equation modeling (SEM) suggested that AMF communities in topsoil and subsoil of maize and wheat responded in differences in soil available P, soil organic carbon, fertilization and climate (temperature and/or rainfall). Fertilization and available N, not AMF community, had significantly positive effects on wheat and maize aboveground dry matter and grain yield. Results from the present study shed light on how AMF communities in topsoil and subsoil respond to different soil fertility management over the long-term. Insights of this study are valuable in managing an important part of biological soil fertility.

Effect of Chemical and Organic Fertilization and Aztobacter Chorocoocum inoculation in IAA Acid and Growth plant (Lycopersicon esculentum Mill)

This study was executed for the spring tomato (Lycopersicon esculentum Mill) for the year 2019 in a field within the Thuraya project-Qadisiyah Governorate, Mineral fertilizer NPK was used with three levels, organic fertilizer (composed poultry) with three levels, and a biological fertilizer consisting of Aztobacter chorocoocum bacteria after Than isolating and diagnosing them. The results of the treatment of half of the fertilizer recommendation in combination with the third level of organic fertilizer and bio-fertilizer gave results that do not differ significantly from the treatment of the full fertilizer recommendation in the above triple interference in soil and plant characteristics (IAA, average plant height), and this indicates the importance of the role of organic and biological fertilizers in Minimize mineral fertilizers.

Effect of chemical and organic fertilization and Aztobacter chorocoocum inoculation on the bacterial biomass and yield of tomato plant (Lycopersicon esculentum Mill)

The tomato crop (Bride of Spring) 2019 was planted in a field within the Thurima project Al-Qadisiyah Governorate, and the mineral NPK fertilizer was used in three levels, organic fertilizer (composed poultry) with three levels and a biological fertilizer consisting of Aztobacter chorocoocum bacteria after that. Isolation and diagnosis of it on two levels. The results of the treatment of half the recommendation of compost in combination with the third level of organic fertilizer and bio-fertilizer gave results that do not differ significantly from the treatment of the recommendation of the full fertilizer in the above triple interaction in soil characteristics and plants (Total Bactiria, The productivity of one plant) This indicates the importance of the role of organic fertilizer Bio-reduction in mineral fertilizers.

Some Nutrients Availability in Rice Soil under Utilization of Organic and Inorganic Fertilizers

A field experiment was conducted at the Experimental Farm of Sakha Agricultural Research Station; Kafr El-Sheikh, throughout the summer season of 2017 and 2018 to examine the nutrients status in rice soils under the utilization of organic and inorganic fertilizers. Egyptian hybrid rice one (EHR1) variety was used. The experiment was laid out in a split-plot design with four replications, where main plots were assigned to NPK fertilizer treatment and sub-plots were allocated to organic material treatments. The NPK fertilizer’s treatments were full dose, 2/3, 1/3 of NPK recommended doses and control (without any mineral fertilizers application). The recommended doses of NPK are 165 kg N ha-1, 36 kg P2O5 ha-1 and 58 kg K2O ha-1. The organic material treatments were control (without any organic materials application), rice straw compost, farm yard manure, chopped rice straw and mixture of chopped rice straw and farm yard manure (1:1). The application rate of the organic materials was 7 tons ha-1 for each treatment. The studied characteristics were the available ammonium (ppm), nitrate (ppm), phosphorus (ppm), potassium (ppm), zinc (ppm) as well as grain yield (t ha-1). Soil samples were collected at 30, 45 and 60 days after transplanting (DAT) and after rice harvest during the two study seasons. The available nutrients in soil tended to increase as NPK fertilizer levels increased and by the application of organic materials. Available NH4 markedly increased after flooding reached its high peak at 30 DAT and then declined to the minimum values at harvest. The high peak of NO3 was observed at 30 DAT, then started to decline afterward and reached its minimum values at harvest. The highest amount of available K was obtained at 45 DAT and then decreased continuously with crop growth, reaching the lowest values at harvest time. Current data reveal that the maximum available Zn was found at 30 DAT. The application of a full recommended dose of NPK mineral fertilizer combined with compost or farm yard manure and compost alone produced the highest values of grain yield.

Green Seaweed Extract (Ulva Lactuca) as a Model for Bio Stimulating and Reducing of Chemical Fertilization on the Growth and Yield of Sweet Potato Plants.

In this research, during the 2016 and 2017 summer seasons, two field experiments were performed at the Agricultural Experimental Station Farm (Abies region), Faculty of Agriculture, Alexandria University. The study investigated the possibility of lowering NPK levels to 75%, 50% and 25% below the recommended level for NPK fertilization; in addition to the recommended fertilizer level of NPK 100% as a control treatment, also, the application of a foliar spray of seaweed extract (SWC) at 0, 5, 10, and 15% concentrations, and their interaction between NPK fertilizer levels with various seaweed extract concentrations (SWC), on vegetative growth, yield and its components as well as on some chemical compositions characteristics of tuber roots. The results showed that the gradual increase in NPK fertilizer levels was accompanied by significant increases in the growth, yield and its components of sweet potato, as well as in the chemical composition of roots. In both growing seasons, the spraying of sweet potato with SWC at a concentration of 15 % resulted in a positive response to all characteristics. The application of NPK mineral fertilizer at 75% of the recommended, interacted with SWC at the concentration of 15%, was generally the most efficient treatment combination that gave the best sweet potato growth, yield and tuber root chemical compositions. In this respect, by using a foliar spray of 15 % SWC , the NPK fertilization can be decreased by 25 % without sacrificing the output value of the sweet potato concerning the amount and quality.

Predicting the influence of fertilization regimes on potential N fixation through their effect on free-living diazotrophic community structure in double rice cropping systems

Free-living nitrogen fixation (FLNF) by diazotrophs is a ubiquitous renewable resource and may constitute an attractive viable solution to the problem of environmental degradation caused by nitrogen over-fertilization. However, the biotic and abiotic control mechanisms of free-living nitrogen fixation are poorly understood. Moreover, there is rare information to link the composition and functions of diazotrophic communities; additionally, there are insufficient or inadequate predictors of the potential N fixation rate (PNFR) to help improve fertilization strategies. Here, through high-throughput sequencing, network analysis, and 15N2 labelling methods, we investigated the long-term effects of partial substitution of mineral N by organic fertilizers on diazotroph abundance and composition in double rice cropping systems. The field trial was conducted for 34 years and included five treatments: control without fertilizer (CK); only mineral NPK fertilizer (NPK); 70% inorganic N + 30% organic N + PK (NPKM1); 50% inorganic N + 50% organic N + PK (NPKM2); 30% inorganic N + 70% organic N + PK (NPKM3). Our results revealed that at the same nutrient input level, increasing the percentage of organic N substitution reduced diazotrophic abundance. Compared with the CK and NPK treatments, the organic substitution regimes reduced the fluctuation range of the PNFR between the early and late rice growing seasons. NH4+-N was the primary factor that negatively correlated (p < 0.01) with diazotrophic abundance, while the potential N fixation rate was positively correlated (p < 0.01) with soil C/N. Among abiotic factors, the models incorporating soil C/N and Fe2+/Mo could accurately predict the potential N fixation rate. High-throughput sequencing and network analyses revealed that Bradyrhizobium and Geobacter were the dominant genera in diazotrophic co-occurrence and keystone taxa patterns under all fertilization regimes. Soil pH and NH4+-N were the most important factors in shaping the diazotrophic co-occurrence and keystone patterns in paddy soils, respectively. Diazotrophic keystone composition was more suitable for predicting and characterising the potential N fixation rate than the co-occurrence pattern of diazotrophs. Moreover, compared with the CK and NPK regimes, partial substitution of mineral N with organic N fertilizer improved the prediction accuracy of potential N fixation rate more effectively. Overall, we highlight the benefits of organic substitution fertilizer regime in stabilizing and improving the potential N fixation rate. Our findings provide relevant insights into the potential of key microbial taxa for predictive N fixation for optimising chemical N fertilizer application strategies in paddy soils.

Effects of Different Biogas Manures and Their Extracts on Dry Matter Yield and Nutrients Uptake by Faba Bean (vicia faba l.) Grown on Sandy Soil Conditions.

The current study evaluates the feasibility of amending a sandy soil with three different types of biogas manure (cattle dung alone BMC, cattle dung + jaw’s mallow wastes BMJ and cattle dung + mango wastes BMM) and their extractions (potassium humate HK, humic acid HA and fulvic acid FA) at two different rates (2 and 4%) to increase NPK uptake by faba bean plants and enhance their growth. To attain this aim, a pot experiment was conducted for 60 days during the winter season of 2019 following a randomized complete block design (RCBD). A control treatment, that received the recommended dose of NPK mineral fertilizers, was also considered for data comparison. Results reveal that the BMC biogas manure recorded the highest increases in faba bean dry weights (6.40g/pot) comparing with the results of other biogas manures. Generally, biogas manures seemed to be more efficient than their extracts on improving NPK uptake by plants and hence increase plant dry weights. Moreover, increasing the rate of application from 2 to 4% recorded further significant increases in this concern. On the contrary, BMM biogas manure was the least efficient organic treatment that increased faba bean growth when applied at a rate of 2% (4.72 g/pot). Thus, it can be deduced that different biogas manures enhanced the uptake of N P K by plants and increased their growth vs the control, especially when applied at a rate of 4%; yet the behavior of the organic amendments in soil varied considerably among the source of the organic amendment.

Rational utilization of Chinese milk vetch improves soil fertility, rice production, and fertilizer use efficiency in double-rice cropping system in East China

ABSTRACT This study aimed to explore the effect of Chinese milk vetch (CMV) on soil fertility and rice production in double rice cropping systems. A field experiment was conducted including the following six treatments: Ck (no NPK mineral fertilizer and no CMV), CMV0 (NPK mineral fertilizer and no CMV), and CMV1–4 (NPK mineral fertilizer and 7500 kg ha−1 CMV, 15,000 kg ha−1 CMV, 22,500 kg ha−1 CMV, 30,000 kg ha−1 CMV) from 2008 to 2018. The results showed that the application of CMV enhanced the organic matter, the total nitrogen, the available phosphorus, pH, and enzyme activities (except for the cellulase) in paddy soils. The organic matter and total nitrogen of CMV3 were increased by 15.99% and 8.07% compared with CMV0 and the increase rate of the organic matter and total nitrogen was by an average of 0.413 and 0.029 g kg−1 per year compared with the initial soil, respectively. The CMV return also improved the enzyme activities (except for the cellulase). Meanwhile, the CMV returned to soil increased dramatically the yields of early rice, late rice, and double rice by 13.46%-26.23%, 13.63%-20.84%, and 13.55%-25.76% compared with CMV0, respectively. The yields of early rice, late rice, and double rice of the CMV3 were highest among all the treatments. The application of CMV improved the agronomic efficiency (AE) and the partial factor productivity (PFP), especially for CMV3. The AE and PFP values of double rice for CMV3 increased by 64.54% and 25.76%, respectively. The application of CMV also increased the sustainability index and reduced the coefficient of variation of the rice yields. In addition, there was negative linear relationship between the amount of CMV needed to generate higher yields of double rice and the years of CMV application. In conclusion, CMV addition at 15,000–22,500 kg ha−1 combined with mineral fertilizer had beneficial effects on the productivity, the stability of rice yield as well as the fertilizer efficiency in double rice cropping system.

The Effect of Fertilization with Spent Mushroom Substrate and Traditional Methods of Fertilization of Common Thyme (Thymus vulgaris L.) on Yield Quality and Antioxidant Properties of Herbal Material

This experiment was designed to determine the effect of spent mushroom substrate, farmyard manure, and mineral fertilization with nitrogen, phosphorus, and potassium on the yield and quality of raw material obtained from two cultivars (“Słoneczko” and “De Dolj”) of common thyme. Unfertilized plots with thyme crops were included as the control treatment. Different row spacings (30 cm and 40 cm) represented the second experimental factor. The highest total yield of thyme raw material was found in the treatment with mineral NPK fertilization, but also in the treatments where spent mushroom substrate (SMS) and mineral NPK fertilization were applied at a ratio of 50:50%. Fertilization with SMS alone (100%) yielded smaller production effects, but they were higher than in the case of fertilization with manure. The high suitability of spent mushroom substrate applied alone or supplemented with mineral fertilization at different rates in spring was confirmed by the best quality parameters and antioxidant properties of the raw material. The use of a wider row spacing (40 cm) resulted in a higher yield of thyme raw material than in the case of a narrower one (30 cm). The narrower row spacing significantly positively affected some of the analyzed quality parameters of the harvested raw material, such as: essential oil content, polyphenol content, and antioxidant activity. The thyme cultivar “Słoneczko” proved to be absolutely more beneficial in terms of yield quantity and quality than the foreign cultivar “De Dolj”.

Effects of long-term fertilization on calcium-associated soil organic carbon: Implications for C sequestration in agricultural soils

Although the contribution of calcium ion (Ca2+) to stabilizing organic carbon (OC) in soils has been known for years, we still have a limited understanding of the quantity and molecular composition of Ca2+ bound SOC (Ca-OC) evolution in response to long-term fertilization. Here we report the role of Ca2+ in the accumulation of OC in the topsoil (0–20 cm) from two long-term (25–37 years) fertilization experiment sites. Approximately 4.54–19.27% and 9.00–25.15% of SOC was bound with Ca2+ in the Ferric Acrisol and Fluvic Cambisol, respectively. The application of NPK mineral fertilizers (NPK) decreased (p < 0.05) the Ca-OC stocks from 3.40 t ha−1 to 0.96 t ha−1 and from 2.03 t ha−1 to 1.17 t ha−1 in the Ferric Acrisol and Fluvic Cambisol, respectively. Swine manure (M) addition did not change (p > 0.05) the Ca-OC stock in Ferric Acrisol, but enhanced (p < 0.05) that from 2.03 t ha−1 to 9.75 t ha−1 in Fluvic Cambisol. Fourier transform infrared and carbon (1s)-near X-ray absorption spectroscopies showed that Ca2+ was mainly bound with aromatic carbon and carboxylic carbon. Long-term M fertilization facilitated the binding of Ca2+ with O-alkyl C, suggesting an increment of Ca-linked polysaccharide. Calcium ion was preferentially associated with 13C enriched organic matter (OM). Mineral fertilization promoted the 13C-enriched organic compounds in the Ca-OC, while organic fertilization facilitated the binding of 13C-depleted organic C with Ca2+. This study suggests that Ca-OC may be a potentially vital and stable OC pool in arable soils, and provides direct evidence for the preferential association of OC with Ca2+ in edaphic environments.