Chemical NPK Research Articles

Small wetted proportion of drip irrigation and non-mulched treatment with manure application enhanced methane uptake in upland field

Methane oxidation in upland areas plays a critical role in the global methane budget. A three-year field experiment was conducted to investigate the effects of two soil surface treatments including soil covered with black plastic film mulch (BM) and non-mulched treatment (NM), three fertilizer treatments including chemical NPK fertilizer (CF), cattle manure (CM) and their combined application of 50% chemical NPK fertilizer and 50% cattle manure (CF+CM), and three soil wetted proportion levels under drip irrigation including: 35% (P1), 55% (P2) and 75% (P3) on methane oxidation in potato field in the arid area of northwestern China. Results showed that seasonal cumulative methane uptake value was 1.1–4.9 kg hm−2 in potato upland fields. BM treatment decreased seasonal cumulative methane uptake by 17%–50% compared to NM treatment through increasing average soil temperature by 2.0–2.5 °C, increasing average irrigation interval by 0–15% and its barricade effect of gas exchange. CM treatment increased seasonal cumulative methane uptake by 7%–9% and 14%–108% in contrast to CF+CM treatment and CF treatment, respectively, due to the low nitrogen content under CM treatment. Different soil wetted proportions didn't significantly affect methane oxidation, while 35% of soil wetted proportion had the greatest methane oxidation rate. Methane flux was quadratically correlated (p = 0.001) to soil matric potential, and the optimal soil matric potential for methane oxidation was −24 kPa. In summary, this study investigated methane uptake in potato farmland contributing to methane flux budget estimation. Manure applied without mulch had more advantage on methane oxidation, and a soil wetted proportion level of 35% was recommended in this study, for favorable for methane oxidation.

Effects of long-term application of organic fertilizer on improving organic matter content and retarding acidity in red soil from China

Long-term fertilization causes declines in soil quality and crop yield, hindering current agricultural development. This paper is about the effect of long-term fertilization (20 years) in Hunan’s Qiyang County. It was found that chemical nitrogen, phosphorus, and potassium (NPK) fertilizer lowered soil pH by an annual average of 0.07, while organic fertilizer increased soil pH by about 0.04. Furthermore, organic fertilizer and chemical fertilizer both increased total soil organic carbon (SOC). Long-term chemical NPK and organic fertilizer increased straw and grain yield of wheat and maize to a greater extent than did other fertilization methods. Thus, our results suggest that mixing organic fertilizer with chemical NPK fertilizer should prevent soil acidification and elevate crop yield.

Effect of the fertilization and growth promoting microrganisms on Schizolobium parahyba

The objective of this work was to evaluate the effect of the chemical and biological fertilizing on the development of two varieties of Schizolobium parahyba, paricá and guapuruvú. The chemical fertilizer NPK 20-05-20 and the plant growth promoting microorganisms, Rhizobium sp. (Rhi) and Rhizophagus clarus (Arbuscular Mycorrhizal Fungus - AMF). The experimental design was a randomized complete block with five replicates and eight treatments. Forty-six day old seedlings of each variety were planted in pits containing hydroretent gel. Then the treatments were added: 1. Control; 2. Rhi; 3. AMF; 4. NPK; 5. Rhi + NPK; 6. Rhi + AMF; 7. AMF + NPK; 8. Rhi + AMF + NPK. Plant length, stem diameter and survival in the environment were evaluated. The ANOVA followed by the Duncan test (? = 0,05) was used to compare the means of the treatments. In the four evaluated periods (37, 111, 250 and 360 days), both varieties had a positive effect on height, diameter and survival when applied to NPK treatments. The interaction AMF and Rhizobium sp. favored the growth in diameter of the guapuruvú. For paricá variety that same treatment provided higher growth in height, however, AMF impaired development in diameter of this variety. Thus, it was observed that under low fertility conditions, the interaction AMF + Rhi favored a greater resistance of guapuruvú to abiotic stress compared to treatment 3, and the presence of grasses in the experimental area may have contributed to the reduction on the development of S. parahyba.

Effect of the Organic and NPK Fertilizers on the Growth and Yield of Sweet Potato (Ipomoea batatas (L) Lam) in the Centre of Côte d’Ivoire

In Côte d’Ivoire, the sweet potato is little cultivated but stays however a culture of pension and a food mattering in certain regions. This study was conducted to assess the effect of the application of mineral (NPK 15-15-15, NPK 12-22-22) and organic (poultry manure) fertilizers on yield components of sweet potato (Ipomoea batatas (L) Lam). The experiment was conducted over two years (2016 to 2017) in experimental station of National Center of Agronomic Research (CNRA) of Bouaké in the centre of Côte d'Ivoire. The experiment was conducted following a split plot with 2 factors (variety and fertilizers) and 3 replicates. The main factor was variety with 2 levels (variety Irene and variety TIB-440060) and the subplot was fertilizers application consisted 13 levels (200, 300, 400, 500 kg ha-1 of NPK fertilizers combined 5, 10, 15 t ha-1 of organic fertilizer). Thirteen treatments based on poultry manure (T6, T7), chemical fertilizer NPK 15 15 15 (T1, T3, T4, T5) and NPK 12 22 22 (T8, T10, T11, T12) and their combination (T2 and T9) were tested. The experimental results revealed that that the effects of chemical fertilizer treatments, manure and their combination with mineral fertilizers did not influence the measured parameters. The results also showed that fertilizers improved all the agronomic parameters of sweet potato compared to the control treatment during two years of experiment. However, the Irene variety with a mean weight of 180 g tuberous roots was significantly different from the TIB variety with a mean weight of 138.73 g.
 In the conditions of our study and over the two-year period, producers of sweet potatoes would benefit from using organic fertilizers with the Irene variety.

Linking methane emissions to methanogenic and methanotrophic communities under different fertilization strategies in rice paddies

Rice paddies are a significant source of atmospheric methane (CH4) threatening global warming. Methane fluxes from rice soils are mediated by both methanogens and methanotrophs, while subject to fertilization regimes. A field experiment was conducted to investigate the response of CH4 emissions, with a close link to methanogenic and methanotrophic communities, to different fertilization strategies over two consecutive rice growing seasons in a paddy field. Four fertilized treatments were established consisting of chemical phosphorous (P) and potassium (K) fertilizer (PK), chemical nitrogen (N) PK fertilizer (NPK), chemical NPK combined with organic manure (NPKM), and organic manure alone (M). Results showed that, relative to chemical PK treatment without N fertilizer input, the application of chemical NPK fertilizer, manure, and their combination significantly increased seasonal mean CH4 emissions by 67.4, 20.4 and 101.2%, respectively. Methane fluxes were significantly and positively (r2 = 0.75) related to mcrA gene copy numbers and the ratio of mcrA/pmoA, while negatively (r2 = 0.40) related to pmoA gene copy numbers, which was mainly regulated by the dynamics of water irrigation regime. The abundance of mcrA and pmoA had trade-off relationship over the rice growing season. In comparison with PK fertilization, N fertilized treatments did not alter the seasonal trend of CH4 fluxes, but enhanced the source strength of CH4 emissions through increased mcrA abundances rather than reduced pmoA-dominated methanotrophic CH4 oxidation in rice paddies. In contrast, N fertilization showed no effect on pmoA abundance and associated methanotrophic community in rice paddies. Results highlight that, given the fertilizer-driven balance between methanogenic and methanotrophic communities, fertilization options with either chemical or organic N input stimulated CH4 emissions mainly through improving soil C substrate and methanogenic activities, especially under the combination of chemical and organic N fertilization in rice paddies.

Evolution over years of structural characteristics of humic acids in Black Soil as a function of various fertilization treatments

Humic substances are the relatively stable and recalcitrant pool of soil organic carbon in the agricultural system. Humic acid (HA) is an active part of soil humic substances. However, little information exists on how structural characteristics of HA evolved with fertilization years in Black Soil. Soil samples were collected in 1997, 2002, 2008, and 2012 from the Long-term Fertilization Station of Black Soil. The methods of 13C-nuclear magnetic resonance spectroscopy, elemental composition analysis, and infrared spectroscopy were employed to analyze the structure of HA. Long-term fertilization had no significant (P > 0.05) effect on the ratio of O and S to C in HA. The ratio of H to C in HA increased with fertilization years after the application of organic manure (M) single or combined with chemical NPK fertilizers. The ratios of aliphatic C to aromatic C, and alkyl C to O-alkyl C in soil HA increased by 7.72% and 20.3%, respectively, in MNPK and M treatments, whereas NPK treatment declined the ratio of aliphatic C to aromatic C by 2.67% compared with CK treatment. The HA structure tends to become aliphatic and simplified with years of organic manure combined with NPK fertilizers. To save costs, organic manure was only applied once within the period of crop rotation and was combined with NPK every year to satisfy crop demands for soil nutrients.

Long-term combined application of manure and chemical fertilizer sustained higher nutrient status and rhizospheric bacterial diversity in reddish paddy soil of Central South China

Bacteria, as the key component of soil ecosystems, participate in nutrient cycling and organic matter decomposition. However, how fertilization regime affects the rhizospheric bacterial community of reddish paddy soil remains unclear. Here, a long-term fertilization experiment initiated in 1982 was employed to explore the impacts of different fertilization regimes on physicochemical properties and bacterial communities of reddish paddy rhizospheric soil in Central South China by sequencing the 16S rRNA gene. The results showed that long-term fertilization improved the soil nutrient status and shaped the distinct rhizospheric bacterial communities. Particularly, chemical NPK fertilizers application significantly declined the richness of the bacterial community by 7.32%, whereas the application of manure alone or combined with chemical NPK fertilizers significantly increased the biodiversity of the bacterial community by 1.45%, 1.87% compared with no fertilization, respectively. Moreover, LEfSe indicated that application of chemical NPK fertilizers significantly enhanced the abundances of Verrucomicrobia and Nitrospiraceae, while manure significantly increased the abundances of Deltaproteobacteria and Myxococcales, but the most abundant Actinobacteria and Planctomycetes were detected in the treatment that combined application of manure and chemical NPK fertilizers. Furthermore, canonical correspondence analysis (CCA) and the Mantel test clarified that exchangeable Mg2+ (E-Mg2+), soil organic carbon (SOC) and alkali-hydrolyzable nitrogen (AN) are the key driving factors for shaping bacterial communities in the rhizosphere. Our results suggested that long-term balanced using of manure and chemical fertilizers not only increased organic material pools and nutrient availability but also enhanced the biodiversity of the rhizospheric bacterial community and the abundance of Actinobacteria, which contribute to the sustainable development of agro-ecosystems.

The links between potassium availability and soil exchangeable calcium, magnesium, and aluminum are mediated by lime in acidic soil

The aims of this study were to investigate the links between potassium (K) uptake by crops and soil K, exchangeable calcium (Ca2+), magnesium (Mg2+), and aluminum (Al3+) when using lime in acidic soil in southern China. Soil samples of three treatments (chemical NP fertilizers, NPK, and NPK plus straw (NPKS)) were collected from a 26-year field experiment (0–20 cm) and then a rhizobox experiment was conducted with seven lime application rates (0–2.26 g kg−1). We investigated the soil exchangeable K+, Ca2+, Mg2+, and Al3+ and non-exchangeable K (NEK) in the rhizosphere soil (RS) and non-rhizosphere soils (NRS), and K uptake by crops. As lime addition rates increased, the average concentration of exchangeable K (EK) in RS under NPK and NPKS treatments decreased to 46.5 mg kg−1 and 70.4 mg kg−1 for maize and wheat, respectively. In treatments with lime application, the NEK concentration was higher in RS and NRS compared with the no-lime in NP treatment but was lower in RS in treatments with K fertilizer input (NPK and NPKS). The K uptake by crops under lime application significantly (p < 0.05) increased by 37.6% to 155.1% compared with the no-lime treatments. Lime application significantly increased soil exchangeable Ca2+ (42.9 to 255.7%) and decreased exchangeable Al3+ (23.7 to 86.6%). According to structural equation modeling, lime indirectly influenced K uptake by crops through its effects on soil exchangeable Ca2++Mg2+ and Al3+, EK, and NEK, which accounted for up to 39% (RS) and 46% (NRS) of the variation in the K uptake by crops. Lime directly and negatively affected EK and NEK in NRS but had no direct effects on EK and NEK in RS. Our results suggested that lime-induced K uptake by crops was mediated by K+, Ca2+, and Al3+, and that lime application resulted in higher soil K availability.

Fertilization modifies the essential oil and physiology of basil varieties

Medicinal and aromatic crops are economically important because they are sources for secondary metabolites such as essential oils (EOs) and polyphenolic compounds. High biomass yields are obtained by conventional chemical fertilizers, whereas the production of EOs is more influenced by elicitors that act on secondary metabolic pathways. The objective of the field trials was to evaluate the effects of biologic and conventional fertilizers (biosolids: 40 and 20 t ha−1, organic: 600 kg ha−1, microorganisms (arbuscular mycorrhizal fungi, AMF): 60 kg ha−1, chemical NPK 20-20-20: 300 kg ha−1) on plant growth, EO chemical profile and yield, and physiology of sweet basil (Ocimum basilicum L.). The two sweet basil cultivars (varieties) used were the green-leafed ‘Aromat de Buzau’ and the purple-leafed ‘Violet de Buzau’. The greatest increases in fresh yields compared with unfertilized plants, 116% and 68% increases for the ‘Aromat de Buzau’ and ‘Violet de Buzau, respectively, were obtained from the conventionally (chemical) fertilized plants. The 40 t ha−1 biosolids treatment increased the EO content of the ‘Aromat de Buzau’ by 30%, while the AMF and organic treatments increased the EO content of the ‘Violet de Buzau’ by 21%. The major constituents of ‘Aromat de Buzau’, methyl chavicol and β-linalool, were increased by 4 and 17% with the AMF and organic treatments, respectively. Eucalyptol and δ-guaiene concentrations in the EO were higher in the 40 t ha−1 biosolids treatment, while τ-cadinol and γ-cadinene were higher in the 20 t ha−1 biosolids treatment. For ‘Violet de Buzau’, the AMF treatment led to an increase of β-linalool, limonene, and (+)-camphor, and decreased the concentration of methyl chavicol. The organic treatment increased the concentrations of limonene, (+)-camphor, terpinene-4-ol, and β-caryophyllene, and decreased the concentration of methyl chavicol. The highest concentration of methyl chavicol was observed in the chemical fertilizer treatment. The 20 and 40 t ha−1 biosolids treatments led to highest yields of eucalyptol, (+)-camphor, terpinene-4-ol, β-caryophyllene, germacrene D, and τ-cadinol. The results demonstrated that conventional fertilizers can increase fresh yield while biological fertilizers positively alter the EO composition, leading to increased crop quality.

Comparative study of Azotobacter with or without other fertilizers on growth and yield of wheat in Western hills of Nepal

A pot experiment was conducted to evaluate the effects of Azotobacter inoculant on the growth and yield of wheat (variety Gautam) at the premise of Lamjung Krishi Campus, Nepal during the winter season of 2016–17. A completely randomized design was chosen with seven treatments (T1, T2, T3, T4, T5, T6, and T7) each replicated three times. The treatments were control (T1), 120:80:80 kg NPK ha−1 (T2), Azotobacter seed inoculated (T3), Azotobacter soil application (T4), Azotobacter + 120:80:80 kg NPK ha−1 (T5), Azotobacter + 10 t FYM ha−1 (T6), Azotobacter + 120:80:80 kg NPK ha−1 + 10 t FYM ha−1 (T7). Root length, root weight, shoot weight, plant height, panicle weight, grain weight, grain yield, total biomass, and biological yield were significantly affected by treatments. Inoculation of Azotobacter only increased 16.5%–19.42% grain yield over control i.e. non inoculated treatments while with other fertilizers increase was of range 19.42%–63.1%. The increase in yield was 23.3% with only chemical fertilizer NPK (T2) over control. So Azotobacter can be used as a biofertilizer for greater yield and the yield is highest with Azotobacter combined with farmyard manure and inorganic fertilizer (NPK).

Response of Two Barley Cultivars to Partial Substitution of Mineral Fertilizers by Biofertilizers under New Valley Conditions

A field experiments was carried out during of 2014/15 and 2015/16 seasons in the Experimental Farm, Agricultural Research Station of El-Kharga, New Valley Government to study the effects of partially substitution of chemical NPK fertilizers by biofertilizers on two barley cultivars production under New Valley conditions. Seven fertilizers combinations were tested as follows: F1: 100% of recommended NPK fertilizers, F2: 75% of recommended NPK fertilizers + Microbein, F3: 50% of recommended NPK fertilizers + Microbein, F4: 75% of recommended NPK fertilizers + Algae extract, F5: 50% of recommended NPK fertilizers + Algae extract, F6: 75% of recommended NPK fertilizers + Algae extract + Microbein, and F7: 50% of recommended NPK fertilizers + Algae extract + Microbein. Number of spikes m-2, number of grains spike-1, weight of 1000-grains, weight of grains spike-1, biological yield fed-1, grain yield fed-1, straw yield fed-1, and harvest index (%) were recorded at harvest. Results indicated that the superiority of Giza 134 cultivar over Giza 132 cultivar was confirmed for most studied traits in both seasons. Double-inoculation of Algae extract and Microbein plus 75% of recommended mineral NPK fertilizers represents 10.14, 18.50 and 16.19% increases in grain, straw and biological yields of barley in the first season; 8.91, 29.42 and 22.15% in the second season, respectively; compared to the application of 100% of recommended mineral NPK fertilizers alone. Giza 134 cultivar fertilized with 75% chemical NPK + Algae extract + Microbein (F6) gave the highest grain yield (2.69 and 2.97 ton fed-1) and biological yield (8.38 and 9.43 ton fed-1) followed by 50% chemical NPK + Algae extract + Microbein (F7) with the same cultivar (2.53 and 2.88 ton fed-1) and (8.16 and 8.95 ton fed-1), respectively. It can be concluded that replacing 25 or 50% of chemical fertilizers by double-inoculation of Algae extract + Microbein as biofertilizers to improved yield and its components of Giza 132 and Giza 134 cultivars as well as saving about 25 to 50% of recommended dose of NPK.

농경지 아산화질소 배출계수의 연간 변동 특성 분석

We aimed at investigating the difference in N₂O emission factors of chemical and organic fertilizers and identifying the main factors influencing annual fluctuations in N₂O emission. We conducted two-year experiments in 2016 and 2017 in an agricultural field planted with sweet potato (Ipomoea batatas). Treatments included chemical NPK fertilizer (NPK) and chicken compost application at 10 ton ㏊SUP-1/SUP, 20 ton ㏊SUP-1/SUP, and 30 ton ㏊SUP-1/SUP rates (CK1, CK2 and CK3). Control was also employed with no addition. Results showed that N₂O emission rates were significantly related with soil water status and soil available N contents. Significant correlation between % water filled pore space (WFPS) and N₂O emission was observed only when the %WFPS was greater than 40% and during the initial stage of the experiment (＜60 d). Comparison of the emission factors in 2016 and 2017 showed us that the emission factor was greater in 2016 when the %WFPS was maintained higher by 16.5% compared to that in 2017. In 2016, the emission factor of organic fertilizer was higher than that of chemical fertilizer, while in 2017, the pattern was reversed. Annual variability in N₂O emission could also be originated from the available N contents remaining in soil after being taken up by plants. If we apply excessive N fertilizer, the soil would contain excess amount of N which was not uptaken by plants, leading to a huge increase in N₂O emission. This case would overestimate emission factor, which was the case for the organic fertilizer in 2016. Over-fertilization should be avoided when we set up an experiment to determine N₂O emission factor.

Soil Olsen-P content changing trend and its relationship with phosphorus surplus and crop yield under long-term fertilization in loessial soil region on the Loess Plateau, China

The changing trend of soil available phosphorus (Olsen-P) content in soil and its relationship with soil phosphorus surplus and crop yield are fundamental when making appropriate phosphate fertilizer recommendations. In this paper, the influences of long-term fertilization on crops phosphorus uptake, soil phosphorus surplus, changing trend of soil available phosphorus content and relationships of soil available phosphorus content with soil phosphorus surplus and crop yield were investigated through 34 years (1981-2015) long-term trial in loessial soil region on the Loess Plateau. The experiment had a completely-randomized-block split-plot design in triplicate. Two main-plot treatments were no farmyard manure and farmyard manure (M), and four subplot treatments were CK (no fertilizer), N (application of chemical fertilizer N), NP (application of chemical fertilizer NP) and NPK (balanced application of chemical fertilizer NPK), respectively. The results showed that fertilization treatments and crop types significantly influenced uptake amount of phosphorus and soil phosphorus surplus. Averaged over time from 1981 to 2015, wheat mean phosphorus uptake amounts of CK, N, NP, NPK, M, MN, MNP and MNPK were 8.63, 10.64, 16.22, 16.21, 16.25, 17.83, 20.39 and 20.27 kg·hm-2, while rape phosphorus uptakeamounts of eight treatments were 4.40, 8.38, 15.08, 15.71, 10.52, 11.23, 17.96 and 17.66 kg·hm-2, respectively. The surplus amount of soil phosphorus significantly correlated with the amount of phosphorus applied to soil. When soil phosphorus surplus amount equal zero, wheat and rape phosphorus input amounts were 10.47 kg·hm-2 and 6.97 kg·hm-2, respectively. Soil phosphorus surplus amount significantly influenced the changing trend of available phosphorus content in soil. CK and N treatments had no phosphorus input, and soil available phosphorus content exhibited a declining trend, annually decreased by 0.16 mg·kg-1 and 0.15 mg·kg-1, respectively. In contrast, NP, NPK, M, MN, MNP and MNPK six treatments were applied with phosphate fertilizer every years, and available phosphorus content gradually increased along with the duration of trial, with annual increase by 0.02-0.33 mg·kg-1. Soil available phosphorus content significantly correlated with phosphorus accumulative surplus amount, and the linear models were y=0.012x+9.33 and y=0.009x+11.72 in manure and no manure treatments, respectively. In no manure treatments, wheat yields significantly positively correlated with soil available phosphorus content, however, in manure treatments, their relationships did not reach a significant level. The relationship of wheat grain yield with available phosphorus content could be significantly fitted by piecewise linear model, and available phosphorus agronomy threshold of wheat was 14.99 mg·kg-1. Rape grain yield also increased with increasing soil available phosphorus content, but the relationship was not significant. This indicated when soil available P content is higher than 14.99 mg·kg -1, application of phosphate fertili-zer should be reduced or even avoided for planting wheat in loessial soil region on the Loess Plateau.

Ureolytic microbial community is modulated by fertilization regimes and particle-size fractions in a Black soil of Northeastern China

Ureolytic microbes are important contributors to N cycling in soil. The distribution of the ureolytic microbial community in different particle-size fractions (2000-250, 250-53, <53 μm) was determined by high-throughput sequencing and q-PCR analyses in 35-year-old fertilization experiment on Black soil. Fertilizer treatments included an unfertilized control, chemical NPK fertilizer, horse manure and NPK fertilizer plus horse manure. Each fertilizer treatment harbored a structurally distinct ureolytic microbial community. The dominant ureolytic microbes were putatively associated with Rhizobiales, Burkholderiales, Rhodocyclales, Pasteurellales, Pseudomonadales, Oceanospirillales, Myxococcales, Micrococcales and Corynebacteriale species. The OTUs associated with the same fertilizer treatment or particle-size fraction were scattered across the phylogenetic tree, and only sequences related to Rhizobiales showed a similar increase in response to manure application. The abundances of ureC genes ranged from 1.5 ± 0.38 × 107 to 9.1 ± 0.91 × 107 g−1 dry soil and accounted for 0.4% to 2.9% of the total bacteria (represented by the copy numbers of the 16SrRNA genes). Significantly lower ureC gene abundance was observed in manure-amended soil, whereas the macro- and microaggregates had higher ureC gene abundances than the silt + clay fraction. The abundance of ureolytic microorganisms was significantly correlated with soil NH4, total nitrogen (TN) and carbon (TC) concentrations. This indicates that variation in ureolytic microbial communities was associated with soil nutrient levels. Urease activities in the particle-size fractions were as follows: microaggregate > macroaggregate > silt + clay. Additionally, urease activities were correlated with the TN, TC and soil organic carbon (SOC) concentrations, but not with the abundances of the ureC genes. In summary, our study first revealed the heterogeneity in the ureolytic microbial communities and activities across different particle-size fractions under long-term fertilization. Microaggregates seems to be a "hotspot" for nutrients, ureolytic microorganisms and urease activity.

Fertilization with inorganic and organic nutrients changes diazotroph community composition and N-fixation rates

Nitrogen fixation by free-living diazotrophs from the atmosphere is an important pathway for nitrogen input into the soil. However, there is little information regarding soil diazotrophic community composition and diversity under long-term fertilization in rice paddy ecosystems. Using the 15N2-tracing method and nifH gene as a molecular marker, we investigated the abundance, structure, and activity of soil diazotrophic community in soil at a 30-year-old filed experimental site treated with four different fertilizer management practices: control (non-fertilization), chemical NPK fertilizers, NPK plus rice straw (NPK+RS), or NPK plus chicken manure (NPK+OM). Among all the treatments, the NPK+OM treatment significantly improved the soil nutritional status. Fertilization increased both bacteria and nifH gene abundances, with the highest values (p < 0.05) found in the NPK+OM treatment. The potential nitrogen fixation rate ranged from 14.6 to 118 μg kg−1 day−1, and the highest rates (p < 0.05) were also observed in the NPK+OM treatment. Long-term chemical NPK fertilization decreased the diversity of diazotrophic community, whereas NPK+RS and NPK+OM treatments maintained the diversity of diazotrophic community. Long-term fertilization changed diazotrophic community as compared to non-fertilization, but there were no significant differences among fertilized treatments. Most nifH sequences were closely linked to Alphaproteobacteria, which was dominated by the genera Bradyrhizobium. Relatively higher Cyanobacteria abundances were observed in the unfertilized soil as compared with fertilized soil. Our results suggest that long-term fertilization increased the abundance of diazotrophs and changed their community structure, and combined use of chicken manure and chemical NPK fertilizers can significantly improve the activity of diazotrophic community.

Utilization of Compost and Compost Tea for Improving Egyptian Hybrid Rice One Cultivar

Presently, Compost and compost tea with additional chemical fertilizers increase the organic carbon and soluble salts of soil, finally enhance the productivity of Egyptian hybrid rice one (H1). A field experiment was conducted in two successive seasons 2015 and 2016 at the experimental farm of Rice Research and Training Center (RRTC), Sakha, Kafrelsheikh, Egypt; to evaluate the influence of different chemical fertilizers (NPK) levels with combined compost and compost tea on yield, yield attributes, chemical compositions and quality of grains of Egyptian hybrid rice one. A randomized Complete Block Design with four replications was used. The results indicated that there were significant positive effects of chemical NPK fertilizers with compost and compost tea on number of panicles m-2 at harvest, filled grain percentage, 1000-grain weight, N uptake in grain and straw, phosphorus and potassium content as well as grain quality. Combination of chemical fertilizers with compost and compost tea were gave the maximum crop yield as well as all the previous characters higher than for the single application of organic or chemical fertilizer alone. Thus, it concluded that the applying N110P24K40 + compost as organic fertilizer + compost tea as bio-organic fertilizer could be used successfully to enhance the productivity of Egyptian hybrid rice one, without any significantly differences with N165P36K60 as recommended NPK doses. Integrated use of chemical NPK fertilizer with compost or compost tea positively affected the yield attributes and yield of hybrid rice and contributed in reducing chemical NPK fertilizers by 1/3 as well as minimizing the cost of inputs and environmental pollution.

EFFECT OF DIFFERENT TYPES OF ORGANIC FERTILIZER IN VEGETATIVE GROWTH OF CACATS ( ALOE VERA L.)

An experiment was carried out on the Cactus (Aloe vera L.), two year old plants were planted in one of the fields of Agriculture College - Baghdad University for the season 2015-2016 and planted in pots. The different organic fertilizers used in two (Sewage, poultry manure and sheep manure) and the fertilize used at two levels 7.5% and 5% from the weight of the pot, and organic acid (Com Sol ) at two levels (1.5 and 3) ml and chemical fertilizer NPK (2.5 gm) in addition to control treatment. The experiment carried out within the RCBD with three replicates and four plants for each experimental unit. results were indicated that the sewage treatment at 7.5% caused significantly increased in rates of vegetative characteristics: leaves number (17.43 leaves per plant), offset number (10.57 offset per plant), plant height and width leaf (64.79 and 7.85) cm respectively, thickness leaf (2.24 mm), gel and cortex dry weight (9.96 and 27.21) gm respectively, and amount of chlorophyll (1.948 mg.gm-1 fresh weight) compared to the control treatment.

Effects of long-term fertilization on organic nitrogen fractions in aquic brown soil

The purpose of present research was to investigate how different fertilization regimes altered soil organic nitrogen fractions and their inter-annual dynamics based on a series of long-term experiment (initiated at 1990), including: CK (non-fertilization); M (recycled pig manure); NPK (chemical fertilizer NPK); NPK + M (recycled pig manure with chemical fertilizer NPK). The results showed that soil organic nitrogen components under the different fertilization treatments presented contrastive patterns from the establishment the experiments to 2015. Generally, acid hydrolysable organic nitrogen content increased year by year. The amino acid nitrogen content under CK and NPK treatments consistently declined, although amino acid nitrogen for M and NPK+M treatments showed a increasing trend. These phenomena were probably ascribed to the utilization of soil amino acids by microbes. From 1990 to 2015, NPK treatment substantially elevated the content of acid-released ammonium nitrogen by 31.1% compared with CK (mean value across the experiment), and for the treatments using organic manure (M and NPK+M), the contents of all fractions of soil organic nitrogen increased. Notably, the increase magnitudes for NPK+M were more dramatic than those of M. These results demonstrated that combined use of organic and inorganic fertilizers could more effectively elevate soil organic nitrogen, subsequently helping to improve the capacity of soil nitrogen supply and enhance the soil fertility.

EFFECT OF DIFFERENT TYPES OF ORGANIC FERTILIZER ON SOME SECONDARY METABOLIC COMPOUNDS PRODUCT OF CACTUS (ALOE VERA L.)

An experiment was carried out on the Cactus (Aloe vera L.) , which two year old was planted in one of the fields of College of Agriculture - University of Baghdad during 2015-2016. The different organic fertilizers used in two (sewage, poultry manure and sheep manure) and the fertilizer used at two levels (5 and 7.5)% from the weight of the pot, and humic acid (Com Sol) at two levels (1.5 and 3) ml and chemical fertilizer NPK (2.5 gm) in addition to control treatment. The experiment carried out within RCBD at three replicates and four plants for each experimental unit. The results showed that the sewage treatment 7.5% significantly increased in concentration of Aloin, Aloe-emodin and Barbolin (175.6, 412.1 and 175.6 µg.gm-1 ) respectively. The treatment of NPK caused significantly increased compare with the other treatments and this treatment gives high percentage to nitrogen, phosphor and potassium which were 1.297%, 0.213% and 1.84% respectively, and also the NPK treatment gives high concentration for amino acid which were Glutamate, Lucien and Methionine (93.44, 65.730 and 40.550) µg.gm-1 respectively.

Significant residual effects of wheat fertilization on greenhouse gas emissions in succeeding soybean growing season

Many efforts have been made to learn the fertilization effects on greenhouse gas (GHG) emissions in the current crop season of multiple cropping systems, however, residual effects on the succeeding crop season are not clear. Based on a thirty-year fertilization experiment, we investigated the impacts of wheat fertilization on GHG emissions in the succeeding soybean season. There were five fertilization regimes for the wheat-soybean cropping system, including sole organic manure (M), balanced chemical NPK fertilizer (NPK), chemical NPK plus manure (NPKM), chemical NP plus wheat straw (NPS), and no fertilizer application (CK). Fertilization significantly affected GHG emissions not only in the current fertilizing season of winter wheat but also in the non-fertilizing season of summer soybean. Compared to the NPK treatment, the M and NPKM treatments stimulated annual soil CO2 and N2O emissions, and reduced CH4 emissions. The M and NPKM treatments also significantly increased soil organic C and total N contents, soil microbial biomass C and N, and NH4N and NO3N concentrations, especially in the soybean season. Although fertilizers were only applied in wheat season, the emissions of CO2 and N2O were higher in the soybean season. At the cropping system scale, the treatments of M and NPKM significantly increased annual global warming potential (GWP) by 75.5% and 38.3%, respectively, compared to the NPK. Sole manure application (M) significantly increased greenhouse gas intensity (GHGI) in comparison with the NPK, while there was no significant increment in the GHGI caused by the treatments of chemical fertilizer plus manure (NPKM) and crop straw (NPS).