Effects Of Long-term Fertilization Research Articles

Long-term growth effects of simulated-drought, mid-rotation fertilization, and thinning on a loblolly pine plantation in southeastern Oklahoma, USA

Loblolly pine (Pinus taeda L.) is the most productive commercial softwood species in the southeastern USA. More frequent drought due to climate change will likely alter loblolly pine productivity, especially in areas where the climate is already highly variable such as the Upper Gulf region of the south-central USA. In a long-term study, we examined the effects of drought treatment (30% throughfall exclusion), fertilization, and thinning on a loblolly pine plantation growing in southeastern Oklahoma, USA to determine how nutrient availability and stand density interact with drier conditions to affect productivity. Our treatments were applied at mid-rotation: throughfall reduction ages 5 to 13, fertilizer ages 5 and 10, and thinning age 10. Treatment effects on diameter and height increment depended on year, with drought treatment tending to decrease diameter and height growth in drier years and fertilization having a stronger positive effects on diameter growth in the years closely following fertilization events. The net effect on standing volume was that fertilization (+7%) and simulated-drought (−8%) countered each other by age 13. Positive fertilization effects were supported by increased foliar nitrogen (N) and phosphorus (P) concentrations, along with increased leaf area index (LAI, +14% measured age 12). Three and four years after thinning, diameter increment increased by 38%, and positive fertilization effects on gross current annual increment were greater in thinned compared to non-thinned stands. Basal area increment in drought-treated stands relative to non-drought-treated stands decreased more during drier years and exhibited recovery during wetter years. The fairly small growth decline in response to 30% throughfall reduction, positive fertilizer effects, and possible post-drought recovery indicate continued plantation viability in the future even at the drier, western fringe of loblolly pine’s commercial range.

Effects of Long-Term Application of Chemical Fertilizers and Organic Fertilizers on Heavy Metals and Their Availability in Reddish Paddy Soil

To investigate the effects of long-term fertilization on the accumulation and availability of heavy metals in reddish paddy soil and to analyze the major influencing factors, soil samples were collected after the later rice was harvested in 2018 from a long-term fertilization field experiment that began in 1984. Six treatments were selected, namely CK (control without fertilization), PK (P and K fertilizer), and NPK (N, P, and K fertilizer), and different proportions of organic fertilizer plus chemical fertilizer (M1NPK: 30%M+70%NPK; M2NPK: 50%M+50%NPK; and M3NPK: 70%M+30%NPK), soil chemical properties, total and available heavy metal contents, and the relationships between the available forms of heavy metals and soil chemical parameters and total heavy metals (THM) were analyzed. The results showed that ① long-term fertilization changed the soil chemical properties; compared with those of CK, PK significantly increased the contents of soil available phosphorus (AP) and available potassium (AK), NPK significantly increased the soil organic matter (SOM), cation exchange capacity (CEC), AP, and AK, and the organic fertilizer treatments significantly increased the contents of SOM, CEC, AP, AK, and nitrate (NO3--N). ② There were slight variations in the THM contents under the chemical fertilizer treatments (PK and NPK), whereas the organic fertilizer treatments significantly increased the total contents of Cu, Zn, and Cd. ③ The chemical fertilizer treatments significantly increased the available Cr and As, whereas the organic fertilizer treatments significantly increased the available Cu, Zn, Cr, Cd, As, and Fe. ④ There were significant positive correlations between the available Cu, Zn, Cr, Cd, As, and Fe and the SOM, CEC, AP, and NO3--N. In addition, the available Zn and Cd were significantly positively correlated with the soil pH, whereas the available Pb was significantly negatively correlated with soil pH, SOM, CEC, and NO3--N. ⑤ There were significant positive correlations between the available and total contents of Cu, Zn, and Cd, whereas there were significant negative correlations between the available and total contents of Cr and Fe. ⑥ Redundancy analysis showed that SOM and pH accounted for 80.7% and 5.5% of the variation in THM, whereas the soil CEC, AP, and pH accounted for 81.1%, 4.9%, and 3.3% of the variation in the available heavy metals, respectively. ⑦ The partial least squares path model analysis showed that the path coefficients of the THM, CEC, and AP on the available state of heavy metals were 0.459, 0.417, and 0.293, respectively. Long-term application of organic manure, such as pig manure, significantly improved the soil chemical properties and affected the availability of heavy metals, and soil CEC and AP may play key roles in regulation.

Long-term effect of crops and fertilization on soil eco-chemical state

Abstract The study on long-term effects of various crops and fertilization practices on soil eco-chemical state was performed in the complex of Planosols at the Warsaw University of Life Sciences – SGGW experimental station in Skierniewice. The study covered three experiments – Ex-1 (established in 1923; no organic fertilization, cereals as a crop), Ex-2 (established in 1992; farmyard manure application every 4 years, cereals as a crop) and Ex-3 (established in 1975; no organic fertilization, blueberries as a crop). Additionally, each experiment covered three mineral fertilization options, including no fertilization, NPK and CaNPK. Soil samples were taken from A-horizons in 2017 and analysed using standard procedures. The results demonstrate considerable influence of crops and fertilization practices on soil eco-chemical state. Both mineral and organic fertilizers positively affected sorptive capacity as compared to control and modified ionic composition of soil sorption complex. Lower exchangeable acidity and higher sum of exchangeable basis and base saturation were noted in fertilized soils and cereals as a crop as compared to controls. Under blueberries there was observed strong acidification of the soil, in particular in combination with NPK fertilizers, as evidenced by the highest exchangeable acidity, hydrolytic acidity, and the lowest base saturation. Liming partially neutralized acidifying effect of blueberries. Fertilization and crops also strongly influenced buffering capacity of the soils. Extremely low ability to neutralize acidic ions was noted in unfertilized soils, whereas the highest at plots fertilized with Ca. The highest ability to neutralize alkaline ions was typical for NPK fertilized soils under blueberries.

Impact of Fertilizer on Crop Yield and C:N:P Stoichiometry in Arid and Semi-Arid Soil.

Fertilization can significantly affect the quality of crop and soil. To determine the effects of long-term fertilization on crop yield and carbon:nitrogen:phosphorus (C:N:P) stoichiometry in soil, a study was conducted on the terraced fields of the Loess Plateau from 2007 to 2019. Nine fertilization treatments were included: no fertilizer; organic fertilizer (O); organic and nitrogen fertilizers (ON); organic, nitrogen, and phosphorus fertilizers (ONP); organic and phosphorus fertilizers (OP); phosphorus and nitrogen fertilizers; potash and nitrogen fertilizers; potash, nitrogen, and phosphorus fertilizers; and potash and phosphorus fertilizers. Under these treatments except for CK and PK, crop yields initially decreased but later increased. The nutrient content and C:N:P stoichiometry increased in soil depth of 0–20 cm. The soil available nutrients did not change significantly with the duration of fertilization. The O, ON, ONP, and OP had the most evident effect on the enhancement of soil nutrient content, whereas O and ON had the most evident effect on the increase in soil organic carbon (SOC):total phosphorus (TP) and total nitrogen (TN):TP. In soil depth of 0–20 cm, crop yield, SOC:TN, SOC:TN, SOC:TP, and TN:TP significantly correlated with soil nutrients. This study indicated that long-term fertilization can effectively improve crop yield, soil fertility, and soil C:N:P stoichiometry. Meanwhile, the single application of an organic fertilizer or the combination of organic and nitrogen fertilizers can improve the condition of nitrogen limitation in arid and semi-arid areas.

An improved microelectrode method reveals significant emission of nitrous oxide from the rhizosphere of a long-term fertilized soil in the North China Plain

Microsensors are able to accurately quantify nitrous oxide (N2O) emissions in microenvironments at high spatio-temporal resolution; yet, limited studies have been conducted on agricultural soils due to the inability to obtain electrical signal under conditions of low soil moisture. This study improved the calibration of a microelectrode for measuring N2O emissions from agricultural soil. The microelectrode was applied to evaluate the effect of long-term fertilization with mineral fertilizer (NPK), complemented with pig manure (MNPK), straw (SNPK), or without fertilizer (CK), all with and without urea addition, on N2O emissions from the soil, with explicit separation of the rhizosphere and the bulk soil compartments. The use of soil solution instead of pure water for calibration of the microelectrode doubled the signal and significantly improved the sensor sensitivity. The optimal electrolytic concentration of the soil solution, expressed as water: soil ratio, was found at the maximum vertex of the quadratic equation fitted on the slope values of the calibration equations for different soil solutions. The application of the calibrated microelectrode revealed significantly higher N2O emission from the rhizosphere compared to the bulk soil, accounting for 60% of the total emission. For the bulk soil, MNPK significantly increased N2O emissions compared to SNPK and NPK, whereas the differences between these treatments for the rhizosphere soil were insignificant. The statistical modeling revealed significant relation of the N2O emission with soil inorganic nitrogen contents and an additive effect of treatment (MNPK and SNPK), urea addition and rhizosphere soil. This study provides novel insights into the use of microelectrodes for measuring N2O emissions from the soil microenvironment and also points on the rhizosphere compartment and the management practices of agroecosystems able to reduce the N2O emission from agriculture.

Changes in Diversity Due to Long-Term Management in a High Natural Value Grassland.

High nature value (HNV) grassland systems are increasingly important for the ecosystem services they provide and for their socio-economic impact in the current constant-changing context. The aim of our paper is to evaluate the long-term effect of organic fertilizers on HNV systems in the Apuseni Mountains, Romania. As an objective we want to identify the optimal intensity of conservation management and its recognition based on indicator value plant species. The experiments were established in 2001 on the boreal floor and analyze the effect of a gradient of four organic treatments with manure. Fertilization with 10 t ha−1 manure ensures an increase in yield and has a small influence on diversity, and could be a real possibility for the maintenance and sustainable use of HNV. Each fertilization treatment determined species with indicator value that are very useful in the identification and management of HNV. The indicator species are useful in forecasting the fluctuations and successions in grasslands, determined by the modification of the dominance-codominance ratio and the real coverage of each species.

Long-term effect of fertilization and manuring on soil aggregate carbon mineralization

The 32 years impact of manuring and fertilization on carbon mineralization in macro- and micro-aggregates in major soil groups of India was studied. Mollisol, Inceptisol, Vertisol, and Alfisol samples were collected (0-15 cm soil depth) from the treatments comprising of control, 100% NPK, 50%NPK+50% N-FYM, 50%NPK+50%N-WR (Wheat residue), 50% NPK + 50% N-GM (Green manure) in the year 2015. The results showed that the mineralizable C pool was significantly higher in treatments applied with 50%NPK+50%N-GM in Mollisol and Vertisol. In Alfisol and Inceptisol, 50% NPK+50% N-FYM and 50% NPK+50% N-GM were significantly higher in both macroaggregates and micro-aggregates protected carbon. Supplementation of fertilizer N either through FYM or various green manuring crops like Sesbania (Sesbania aculeata L. in Inceptisol), greengram (Vigna radiata L. in Mollisol), sunhemp (Crotalaria juncea L. in Vertisol) and karanj (Pongamia pinnata L. in Alfisol) significantly improved mineralizable carbon pool signifying their potential contributions to nutrient cycling and thereby nutrient availability to various crops in the cropping systems in the above soils.

Long term effects of fertilizer and manure application on productivity, sustainability and soil properties in a rice-rice system on Inceptisols of Eastern India

ABSTRACT Long-term application of fertilizer and manure can affect soil properties with implications on the productivity and sustainability of crops. Data from a long-term fertilizer experiment at Bhubaneswar, India was used to study the impact of seven treatments viz. control, application of recommended dose of NPK (NPK), 150% NPK (1.5 NPK), NPK + Zn (NPKZn), NPK + FYM (NPKFM), NPK + Zn + B (NPKZnB) and NPK + Zn + S (NPKZnS) on productivity, sustainability (in terms of sustainable yield index (SYI)), soil properties (physical, chemical and biological) and soil organic carbon (SOC) sequestration of rice-rice cropping system. Results revealed that application of NPKFYM improved the average grain yield and SYI of wet and dry season rice and the system by 36.3, 21.6, and 28.3% and 28.8, 17.1, 22.8%, respectively, over NPK alone. Application of NPKFYM improved soil fertility by stimulating microbial activity, improving soil physical health, resisting drop in pH to more acidity and improving CEC and macro- and micro-nutrients levels. NPKFYM also sequestered higher SOC than NPK alone. Therefore, application of NPKFYM can be recommended for sustaining the productivity of the rice-rice system with improvement of soil health under Inceptisols of Eastern India.

Effect of long-term fertilization on bacterial communities in wheat endosphere

Fertilization has been shown to exert a significant influence on soil microorganisms and directly and indirectly influences plant growth and survival in agroecosystems. However, it is unknown whether fertilization affects endophytic microbial communities, which are ubiquitous and intimately associated with plant growth and health. Herein, we investigated endophytic bacterial communities in wheat leaves and roots under different long-term fertilization regimes, including NPK chemical fertilizer and NPK chemical fertilizer combined with wheat straw, pig manure, or cow manure. Endophytic bacterial community composition considerably differed in leaves and roots. Although different fertilization treatments did not affect the endophytic bacterial species richness or phylogenetic diversity in either leaves or roots, the community composition was significantly altered, particularly in roots. The endophytic bacterial co-occurrence network in leaves was more complex and stable than that in roots. Furthermore, many of the keystone species that were identified by their topological positions in the co-occurrence networks of leaves and roots were involved in plant growth and fitness. The total relative abundance of keystone species was the highest in the NPK plus cow manure treatment in both leaves and roots. Overall, our results suggest that different fertilization regimes can strongly affect endophytic bacterial communities, and the combination of NPK fertilizer and cow manure promoted the relative abundance of the key endophytic bacterial microbiota in both leaves and roots, which might be beneficial for plants in agroecosystems.

Meta-analysis on how manure application changes soil organic carbon storage

Manure application to agricultural soils is widely considered as a source of nutrients and a method of maintaining levels of soil organic carbon (SOC) to mitigate climate change. At present, it is still unclear which factors are responsible for the SOC stock dynamics. Therefore, we analyzed the relationship between SOC stock changes and site characteristics, soil properties, experiment characteristics and manure characteristics. Overall, we included 101 studies with a total of 592 treatments. On average, the application of manure on agricultural soils increased SOC stocks by 35.4%, corresponding to 10.7 Mg ha−1. Manure applications in conventional tillage systems led to higher SOC stocks (+ 2.2 Mg ha−1) than applications under reduced tillage. Soil organic carbon increase upon manure application was higher in soils under non-tropical climate conditions (+ 2.7 Mg ha−1) compared to soils under sub-tropical climate. Larger SOC increases after manure application were achieved in intermediate and shallow topsoils (in 0–15 cm by 9.5 Mg ha−1 and in 16–20 cm by 13.6 Mg ha−1), but SOC stocks were also increased in deeper soils (> 20 cm 4.6 Mg ha−1), regardless of the tillage intensity. The highest relative SOC increase (+ 48%) was achieved if the initial SOC was below 1% but the absolute SOC increased with increasing initial SOC. Clay soils showed higher SOC increase rates compared to sandy soils (+ 3.1 Mg ha−1). Acidic soils showed comparable relative effects but a higher stock difference than neutral (+ 5.1 Mg ha−1) and alkaline soils (+ 5.1 Mg ha−1). The application of farmyard-, cattle- and pig manure showed the highest SOC increases (50%, 32% and 41%, respectively), while green manure and straw showed only minor effects. If manure applications were combined with additional mineral fertilizer, the SOC increases were higher (+ 1.7 Mg ha−1) compared to manure alone. Higher applied amounts generally led to higher SOC stocks. However the annually applied amount is only important under conventional tillage, non-tropical climate conditions, and pH-neutral as well as SOC-rich or SOC-depleted soils and if no additional mineral fertilization is applied. Further studies should focus on the SOC dynamics under tropical climate conditions and factors influencing a potential carbon saturation. In both cases, the number of data was too small. For this reason, additional field studies should be conducted primarily in the tropics. On the other hand, long-term field trials should be re-assessed or newly established to specifically investigate potential saturation effects and long-term (> 20 years) fertilizer effects and carbon sequestration.

Effects of Long-Term Nitrogen Fertilization on the Formation of Metabolites Related to Tea Quality in Subtropical China.

As a main agronomic intervention in tea cultivation, nitrogen (N) application is useful to improve tea yield and quality. However, the effects of N application on the formation of tea quality-related metabolites have not been fully studied, especially in long-term field trials. In this study, a 10-year field experiment was conducted to investigate the effect of long-term N application treatments on tea quality-related metabolites, their precursors, and related gene expression. Long-term N application up-regulated the expression of key genes for chlorophyll synthesis and promoted its synthesis, thus increasing tea yield. It also significantly increased the contents of total free amino acids, especially l-theanine, in fresh tea leaves, while decreasing the catechin content, which is conducive to enhancing tea liquor freshness. However, long-term N application significantly reduced the contents of benzyl alcohol and 2-phenylethanol in fresh tea leaves, and also reduced (E)-nerolidol and indole in withered leaves, which were not conducive to the formation of floral and fruity aroma compounds. In general, an appropriate amount of N fertilizer (225 kg/hm2) balanced tea yield and quality. These results not only provide essential information on how N application affects tea quality, but also provide detailed experimental data for field fertilization.

Long-term differences in nutrient management under intensive cultivation alter potassium supplying ability of soils

Despite removal of potassium (K) by crops in large quantities, often exceeding that of nitrogen (N), K fertilization has long been neglected compared with N and phosphorus (P) in Indian agriculture leading to mining of soil K. We, therefore, studied the effect of long-term fertilization (with or without K) on K supplying ability of two major soil orders of India, viz. Inceptisol and Vertisol after more than four decades of cultivation. Soil samples (0–15 and 15–30 cm) were collected after the completion of 43 (Inceptisol) or 42 (Vertisol) cropping cycles from on-going long-term experiments located at New Delhi (Inceptisol) and Jabalpur (Vertisol), India, from six treatments, viz. no-fertilization (control), recommended N (N), N and P (NP), N, P and K (NPK), 150% NPK and NPK + farmyard manure (NPK + FYM), along with adjacent uncultivated land. Ammonium acetate extractable K (Kex), non-exchangeable K (NEK), quantity-intensity relationship and K release kinetics along with grain yields and K uptake by crops were studied. The Kex and K-saturation of exchange complex in both soils and NEK in the Inceptisol were the lowest under NP followed by N. Cropping without K input resulted in lower quantity (non-specifically and specifically held K i.e. –ΔK0 and Ks) and intensity (equilibrium activity ratio i.e. AReK) of K in both soils. More negative values of standard free energy of exchange (ΔG0) under cultivation without K in both soils indicated increased affinity of soil solids for K+ owing to K omission. The gap between equilibrium exchangeable K (EK0) and minimum exchangeable K (EKmin) was significantly lower under cropping without K than with K in the Vertisol. Imbalanced fertilization (N or NP) also showed noticeably smaller cumulative K releases and slower rates of replenishment of solution K by solid phase K in both soils. Interestingly, even under cropping with K fertilization at either experimental site, several K supply parameters showed decline compared with adjacent uncultivated soil. Grain yields of wheat and total K uptake by all crops (maize and wheat in Inceptisol; soybean and wheat in Vertisol) showed significant and positive response to K application. The study showed variable effect of long-term intensive cropping with or without K input on the K supplying ability of an Inceptisol and a Vertisol. The findings underlined inadequacy of the existing K fertilizer recommendations, and the need for their refinement to minimize native K mining and sustain K supplying ability of soils.

Effects of long-term fertilization without phosphorus on greenhouse gas emissions from paddy fields.

The strategy of few or no-phosphorus fertilization in rice season but more in wheat season can effectively increase phosphorus use efficiency and reduce phosphorus loss through runoff and leaching. It remains unknown whether the lack of phosphorus will affect greenhouse gas emission in the rice season. We monitored the CH4 and N2O emission fluxes during the growth period of rice treated with normal phosphorus application (NPK) and no-phosphorus application (NK) in two long-term experimental fields in Suzhou and Yixing. The results showed that long-term no-phosphorus application promoted CH4 and N2O emission in both fields. Compared with the NPK treatment, CH4 and N2O emissions from the NK treatment significantly increased by 57% and 25% in Suzhou experi-mental field, respectively, while those in Yixing experimental field were also significantly increased by 221% and 70%, respectively. The contents of organic acid, dissolved organic carbon and available phosphorus in soil were reduced under long-term NK treatment, and they were closely related to CH4 emission. Soil available phosphorus content was significantly negatively correlated with CH4 emission (r=-0.987). The global warming potential (GWP) was greater in NK treatment than NPK treatment in both fields. Therefore, long-term no-phosphorus application could decrease the contents of organic acid, soluble organic carbon, and available phosphorus in soils, resulting in more CH4 and N2O emission in rice field.

Effect of Long-Term Organic Fertilization in Flooded Rice Soil on Phosphorus Transformation and Phosphate Solubilizing Microorganisms

Phosphorus (P) is a major limiting factor for plant growth. Long-term organic fertilization increases P availability by improving soil microbial and chemical properties. To study this, rice was grown under different treatments, namely, control, farmyard manure (FYM), green manure (GM), FYM + GM (1:1) (FYGM), FYM + Azolla (1:1) (FYAZ), rice straw (5 t ha−1) + GM (GMRSF), Azolla + GM (1:1) (GMAZ) and rice straw (2.5 t ha−1) + GM (GMRSH), with the aim of comparative evaluation of microbiological and chemical changes occurring in the rice soil after 15 years of rice-fallow cycles. The results showed that organic fertilization increased dehydrogenase activity by 12–50% over the control. Both acid (166.1 μg PNP g−1 h−1) and alkaline phosphatase (46.1 μg PNP g−1 h−1) activities were found highest in GMRSH. Long-term application of organic fertilization increased the pools of active/labile C (microbial biomass carbon, readily mineralizable carbon), N (microbial biomass nitrogen) and P (microbial biomass phosphorus) in the soil. Bacterial and fungal populations were observed higher in the FYM treatment than in the control. However, the populations of phosphate solubilizing bacteria (PSB) and fungi (PSF) were observed highest in GMRSH and FYAZ, respectively. Non-occluded Al and Fe-P (125.94 kg ha−1) was highest in GMRSH, while occluded P (6.46 kg ha−1) was highest in GMRSF. Thus, long-term (15 years) organic fertilization improves PSB and PSF populations, contributing to better P transformation in the soil. GMRSH and GMRSF treatments were found to be effective organic fertilization in increasing enzymatic activities, available phosphate fractions and microbial biomass in soil.

Effects of long-term nitrogen fertilization on N2O, N2 and their yield-scaled emissions in a temperate semi-arid agro-ecosystem

Nitrous oxide (N2O) measured simultaneously with di-nitrogen (N2) emissions from soils are greatly uncertain due to large temporal and spatial variations. This study aims to report N2O, N2, N2/N2O, 15N-N2O, wheat-maize annual grain yields, and yield-scaled N2O and N2O plus N2 emissions on the responses to different nitrogen (N) fertilizer rates in a winter wheat-summer maize cropping system. Furthermore, this study also seeks to determine controlling factors for N2O, N2, and N2/N2O emissions and significantly investigate the relationship between the soil-climate measured factors and 15N-N2O. Three N inputs and control treatments, 0, CK; 200, LN; 400, MN; and 600, HN kg N ha−1 year−1 were set since 1998. Direct measurement method has been used to quantify N2O and N2 emissions. Our results indicated that the effects of long-term N fertilization significantly increased N2O and N2 and also reduced N2/N2O emission ratios as described by exponential functions. Using structural equation modeling (SEM), NH4+, WFPS, NO3-, and DOC were revealed to be main controlling factors for N2O, while N2 by DOC, NO3-, WFPS, and temperature finally N2/N2O was positively related to temperature. Furthermore, the 15N-N2O was positively related to N2/N2O ratios, indicating that denitrification is the dominant process at the study site. The yield-scaled N2O emissions followed the order HM>MN>LN>CK, and they were 1.56, 1.47, and 1.07 times greater than CK, respectively. Total yield-scaled N2O plus N2 were in the order of CK>HN>MN>LN. N fertilization has shown strong impact not only on N2O, N2, and N2/N2O emissions but also on yield-scaled N2O and N2O plus N2 emissions. High agronomic nitrogen use efficiency (NUE), low yield-scaled N2O emissions, and low cumulative N2O plus N2 emissions were observed at 200-LN treatment, suggesting this rate to be an optimum and sustainable agricultural management practice with no significant crop yield reduction as compared to the current farmers’ practice of 400 kg N ha−1 year−1.

Influence of manure fertilization on soil phosphorous retention and clay mineral transformation: Evidence from a 16-year long-term fertilization experiment

Phosphorus (P) has a deficit effect for living organisms, and there is a continuous influx of large amounts of P fertilizers into agriculture systems. However, the low use efficiency of P fertilizers in the current practice of crop production is attributed to the quick fixation effects of soil minerals on the added P fertilizer. This work investigated the effects of long-term manure fertilization on soil P retention and clay mineral phase transformation using X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM) and energy dispersive X-ray spectroscopy (EDS). The manure application with lime significantly mitigated soil acidification, and P retention was significantly correlated with soil colloids. Microanalysis data revealed that clay minerals, acting as the substrate, likely provided plenty of sites for P retention to support the crystallized and amorphous Fe-oxides, which promoted P adsorption/stabilization. The manure addition led to the transformation of soil clay minerals from 2:1 type to 1:1 type, which was related to soil microbial biomass. Taken together, our study suggest that manure fertilization impacts the microbial biomass, and thereby promotes the transformation of clay minerals and further influences the retention and reactivity of P in the soil environment.

Depth profile of plant nutrients and acidity in a non-allophanic Andosol as affected by a half-century of fertilization

ABSTRACT To clarify the effects of long-term fertilization on the depth profile of plant nutrients and soil acidity in non-allophanic Andosols, a soil survey was conducted on fertilized grassland and adjacent secondary forest in Kuju highland, Oita Prefecture, Japan. Both of the experimental plots had been managed as a semi-natural grassland (managed by cutting, mowing, and burning for raising cows) before mid of the 1960s, and then, the former had been converted into reclaimed grassland with applying agricultural materials such as fertilizers, manure, and lime, and the latter had been abandoned which resulted in secondary succession into the secondary forest. The comparison of the depth profiles between the two plots revealed that the applied Ca2+ and Mg2+ reached at least 100 cm depth of the non-allophanic Andosol profile. The soil pH was increased at least at the depth of 100 cm, and the plant-toxic level of soil acidity (≥12 mmol kg−1), which is one of the characteristic properties of non-allophanic Andosols, was decreased in the fertilized grassland soil. Soil available P was also observed to be increased at least 80 to 100 cm depth, although the mobility was smaller than those of exchangeable cations and soil acidity. Other soil chemical properties, such as cation exchange capacity, total C and N contents, pyrophosphate-extractable Al (Alp) and Fe (Fep), acid-oxalate-extractable Al (Alo), Fe (Feo), and Si (Sio), Alp/Alo ratio, and Alo + 1/2 Feo, were not significantly altered by the modern grassland management activities. This study reveals considerable loss of plant nutrients from the fertilized grassland soil of a non-allophanic Andosol during a half-century. The loss of plant nutrients should be reduced for sustainable agriculture and conserving the natural environment.

Effects of Long-Term Fertilisation and Weather on Soil Properties and Spring Barley Yield

The purpose of the experiment was to determine long-term fertilization and the effects of weather on the soil properties and spring barley yields. A long-term field experiment—with crop rotations of potatoes (hemp oil from 2017), spring barley, spring barley with red clover (undersown), and red clover was established in 1960 Kuusiku, Estonia. Different barley varieties was used over the experimental period. With except the spring barley variety 'Anni', which was tested from 1995–2019.The experiment has three fertilizer treatments: the moderate dose of fertilization (NPK1),double NPK1 (NPK2), and moderate fertilization with farmyard manure (NPK1 + FYM). After harvest, the soil samples were collected from 0–0.2 m of topsoil and 0.2–0.4 m of subsoil from each plot, using a soil drill.

Long-term Fertilization with Liquid Cattle Manure Leaves Legacy Nutrients, but not Organic Carbon and Has No Effect on Soil Microbial and Physical Properties a Year after Last Application

ABSTRACT Long-term liquid cattle manure (LCM) application can enhance soil fertility, increase soil organic carbon, and improve soil properties. We investigated the residual effects of long-term fertilization with LCM on physical, chemical and microbial properties of a calcareous soil. The effects of LCM, common inorganic fertilization, recommended fertilization or non-fertilized control were investigated in field plots with corn (Zea mays L.), 1 year after the cessation of 16-years of experimentation. The residual concentrations of soil available P, K, Cu, Zn, B and total N but not NO3-N remained significantly higher with LCM, while there were no differences in soil pH, electrical conductivity and sodium adsorption ratio, compared to the other treatments. The previously observed increase of soil organic C with LCM was no longer evidenced. For aggregate size distribution and stability, microbial biomass N, easily extractable glomalin-related soil protein, number and morphotypes of arbuscular mycorrhizal fungal spores and percentage of root length colonization, there was no difference among treatments. Microbial growth and activity were limited by C, while the calcareous nature of the soil was more important than glomalin for soil aggregation. In conclusion, the residual effects of LCM were limited to soil nutrient increase.

Long-Term Fertilization Shapes the Putative Electrotrophic Microbial Community in Paddy Soils Revealed by Microbial Electrosynthesis Systems.

Electrotrophs play an important role in biogeochemical cycles, but the effects of long-term fertilization on electrotrophic communities in paddy soils remain unclear. Here, we explored the responses of electrotrophic communities in paddy soil-based microcosms to different long-term fertilization practices using microbial electrosynthesis systems (MESs), high-throughput quantitative PCR, and 16s rRNA gene-based Illumina sequencing techniques. Compared to the case in the unfertilized soil (CK), applications of only manure (M); only chemical nitrogen, phosphorous, and potassium fertilizers (NPK); and M plus NPK (MNPK) clearly changed the electrotrophic bacterial community structure. The Streptomyces genus of the Actinobacteria phylum was the dominant electrotroph in the CK, M, and MNPK soils. The latter two soils also favored Truepera of Deinococcus-Thermus or Arenimonas and Thioalkalispira of Proteobacteria. Furthermore, Pseudomonas of Proteobacteria and Bacillus of Firmicutes were major electrotrophs in the NPK soil. These electrotrophs consumed biocathodic currents coupled with nitrate reduction and recovered 18-38% of electrons via dissimilatory nitrate reduction to ammonium (DNRA). The increased abundances of the nrfA gene for DNRA induced by electrical potential further supported that the electrotrophs enhanced DNRA for all soils. These expand our knowledge about the diversity of electrotrophs and their roles in N cycle in paddy soils and highlight the importance of fertilization in shaping electrotrophic communities.