Mineral NPK Fertilizer Research Articles

Long‐Term Influence of Tillage and Fertilization on Net Carbon Dioxide Exchange Rate on Two Soils with Different Textures

The importance of agricultural practices to greenhouse gas mitigation is examined worldwide. However, there is no consensus on soil organic carbon (SOC) content and CO emissions as affected by soil management practices and their relationships with soil texture. No-till (NT) agriculture often results in soil C gain, though, not always. Soil net CO exchange rate (NCER) and environmental factors (SOC, soil temperature [T], and water content [W]), as affected by soil type (loam and sandy loam), tillage (conventional, reduced, and NT), and fertilization, were quantified in long-term field experiments in Lithuania. Soil tillage and fertilization affected total CO flux (heterotrophic and autotrophic) through effect on soil SOC sequestration, water, and temperature regime. After 11 yr of different tillage and fertilization management, SOC content was 23% more in loam than in sandy loam. Long-term NT contributed to 7 to 27% more SOC sequestration on loam and to 29 to 33% more on sandy loam compared with reduced tillage (RT) or conventional tillage (CT). Soil water content in loam was 7% more than in sandy loam. Soil gravimetric water content, averaged across measurement dates and fertilization treatments, was significantly less in NT than CT and RT in both soils. Soil organic carbon content and water storage capacity of the loam and sandy loam soils exerted different influences on NCER. The NCER from the sandy loam soil was 13% greater than that from the loam. In addition, NCER was 4 to 9% less with NT than with CT and RT systems on both loam and sandy loam soils. Application of mineral NPK fertilizers promoted significantly greater NCER from loam but suppressed NCER by 15% from sandy loam.

PHYSIOLOGICAL STUDIES ON CLOVE BASIL PLANT

This experiment was conducted at the Floriculture Nursery at the Experimental Farm and the Laboratory of Floriculture, Fac. of Agric., MiniaUniv. during the two successive seasons of 2010 and 2011 to study the effect of FYM (Farmyard manure), bio. and / or salicylic acid, as well as, mineral NPK fertilization treatments on vegetative growth, oil production and chemical composition of clove basil plant. The obtained results indicated that the application of FYM significantly increased plant height (cm), number of branches / plant, herb fresh weight in each cut (g / plant / cut), herb fresh weight in each season (g / plant / season) and total herb fresh weight per feddan for each season (ton. / fed. / season), essential oil (%), essential oil yield / plant / cut (ml) and per plant / season (ml), as well as per fed. / season (liter), content of chlorophyll a, b and carotenoids (mg / g. fresh weight) in the fresh leaves, as well as, the percentages of N, P and K in the dry herb. The superiority in all previous traits was for treatment of FYM at high level (45 m3 / fed.) as compared with the other levels including the control. The plants treated with mineral NPK or a mixture of effective microorganisms (E.M.) and phosphorein (Phos.) plus salicylic acid gave the best results of all tested parameters in both cuts of the two growing seasons. Regarding the percentage of essential oil in the fresh herb, the treatment of E.M. + Phos. + Sal. was more effective than the other treatments. The interaction between the main-plots (FYM treatments) and sub-plots (bio, Salicylic acid and NPK treatments) had significant effect on the previous parameters. The highest values, in most cases, were obtained due to the high level of FYM (45 m3 / fed.) in combination with mineral NPK and E.M. + Phos. + Sal.

Codigested dairy slurry as a phosphorus and nitrogen source for Zea mays L. and Amaranthus cruentus L.

AbstractResidues from biogas production contain essential plant nutrients such as nitrogen (N), phosphorus (P), and potassium (K) but also organic matter, and should be recycled in crop production. For efficient re‐use as fertilizers, the availability of nutrients for crops and the effect of the residues on soil fertility need to be evaluated. Focusing on the element P, we compared effects of codigested slurry with dairy slurry, highly soluble mineral NPK fertilizer, and a control without any P supply (NK). Codigested slurry used in this experiment was based on anaerobic digestion of dairy slurry, maize silage, and wheat grain. The fertilizing effects were tested in an 8‐week pot experiment on a sandy and a loamy soil using two crop species (Zea mays L., Amaranthus cruentus L.). The plant P uptake was up to 64% greater in the slurry treatments than in the treatment without P. The effect of codigested slurry on P uptake was comparable to that of dairy slurry and mineral P. Plant N uptake from codigested slurry was lower than that from mineral N (NK, NPK), but tended to be higher than from dairy slurry. The water‐soluble and double lactate–soluble P content of the soil was lower in the slurry treatments than in the mineral‐P treatments and accompanied by higher contents of microbial‐bound P. Differences between both organic fertilizers were detected for dehydrogenase activity which was up to 32% lower in soils fertilized with codigested slurry than it was in soils fertilized with dairy slurry. Our results indicate that codigestion of slurries in biogas plants does not substantially alter their fertilizer value as P and N sources for crops.

Physiological Response of Gladiolus Plants to Amino Acid Tryptophan and Mineral Fertilization in the New Reclaimed Lands

Two field experiments were carried out during two successive seasons of 2008/09 and 2009/10 for evaluating the response of gladiolus plant (Gladiolus gandavensis cv.Rosesupreme) to four concentrations ofamino acid at 0.00, 50, 100 and 200 ppm as pre-soaking of corms for 24 hr and four rates of mineral fertilization NPK (19:19:19) at 0.00, 0.25, 0.50 and1.0% at three times as foliar spray. The obtained data showed that pre-soaking of gladiolus corms with tryptophan alone and/or in combination with different rates of mineral NPK, stimulated the vegetative growth characteristics, flowering parameters and production of corms and cormels. The best results of studied parameters were obtained by using 200 ppm of tryptophan treatment with 0.50 and/or l.0% foliar fertilization NPK (19:19:19). Moreover, the results indicated that amino acid at 200 ppm with mineral fertilization at 1.0% gave the highest values of chemical composition parameters( the total chlorophyll (a+b), mineral contents of leaves and total carbohydrates in the new corms).

Influence of organic matter on rheological properties of soil

Recently rheological methods have been used to investigate the mechanical properties of soil micro-structure. Rheological techniques provide a number of quantitative physically based measurements and offer a better understanding of how soil micro-structure behaves when subject to stress. Here a rotational rheometer with a parallel-plate measuring device was used to explore the viscoelastic properties of soil as a function of soil organic carbon (SOC). We used samples from the long-term experimental site at Broadbalk, Rothamsted, UK. Data from amplitude sweep tests (AST) with controlled shear deformation are reported as well as mineralogical data. In general, water content, and SOC content, in addition to soil texture, clay mineralogy, carbonate, and cations all have an effect on stiffness, structural stability, and shear behavior. Storage modulus G′ and loss modulus G″, yield point, the linear viscoelastic range (LVE), loss factor tan δ, and integral z characterize micro-structural properties of soil on the particle-to-particle scale. Long-term applications of farmyard manure (FYM) lead to a significant increase in soil organic carbon (SOC), in comparison with the application of ammonium nitrate in form of mineral NPK fertilizer and bare fallow. For wet soils, increased SOC provided greater resistance to deformation and improved soil elastic properties allowing greater deformation before a yield point was reached. In drier soils however, (−6 and −15kPa) this relationship was less clear.

Cotton pest management practices and the selection of pyrethroid resistance in Anopheles gambiae population in Northern Benin

BackgroundPyrethroid insecticides, carbamate and organophosphate are the classes of insecticides commonly used in agriculture for crop protection in Benin. Pyrethroids remain the only class of insecticides recommended by the WHO for impregnation of bed nets. Unfortunately, the high level of pyrethroid resistance in Anopheles gambiae s.l., threatens to undermine the success of pyrethroid treated nets. This study focuses on the investigation of agricultural practices in cotton growing areas, and their direct impact on larval populations of An. gambiae in surrounding breeding sites.MethodsThe protocol was based on the collection of agro-sociological data where farmers were subjected to semi-structured questionnaires based on the strategies used for crop protection. This was complemented by bioassay tests to assess the susceptibility of malaria vectors to various insecticides. Molecular analysis was performed to characterize the resistance genes and the molecular forms of An. gambiae. Insecticide residues in soil samples from breeding sites were investigated to determine major factors that can inhibit the normal growth of mosquito larvae by exposing susceptible and resistant laboratory strains.ResultsThere is a common use by local farmers of mineral fertilizer NPK at 200 kg/ha and urea at 50 kg/hectare following insecticide treatments in both the Calendar Control Program (CCP) and the Targeted Intermittent Control Program (TICP). By contrast, no chemicals are involved in Biological Program (BP) where farmers use organic and natural fertilizers which include animal excreta.Susceptibility test results confirmed a high resistance to DDT. Mean mortality of An. gambiae collected from the farms practicing CCP, TICP and BP methods were 33%, 42% and 65% respectively. An. gambiae populations from areas using the CCP and TICP programs showed resistance to permethrin with mortality of 50% and 58% respectively. By contrast, bioassay test results of An. gambiae from BP areas gave a high level of susceptibility to permethrin with an average mortality of 94%.Molecular analysis identified An. gambiae s.s, and An. arabiensis with a high predominance of An. gambiae s.s (90%). The two molecular forms, M and S, were also determined with a high frequency of the S form (96%).The Kdr gene seemed the main target- site resistance mechanism detected in CCP, TICP, and BP areas at the rates ranging from 32 to 78%. The frequency of ace-1R gene was very low (< 0.1).The presence of inhibiting factors in soil samples under insecticide treatments were found and affected negatively in delaying the development of An. gambiae larval populations.ConclusionsThis research shows that Kdr has spread widely in An. gambiae, mainly in CCP and TICP areas where pyrethroids are extensively used. To reduce the negative impact of pesticides use in cotton crop protection, the application of BP-like programs, which do not appear to select for vector resistance would be useful. These results could serve as scientific evidence of the spread of resistance due to a massive agricultural use of insecticides and contribute to the management of pesticides usage on cotton crops hence reducing the selection pressure of insecticides on An. gambiae populations.

Soil Total Nitrogen and Natural 15Nitrogen in Response to Long-Term Fertilizer Management of a Maize–Wheat Cropping System in Northern China

The Fengqiu long-term field experiment was established to examine effects of organic manure and mineral fertilizers on soil total nitrogen (N) and natural 15N abundance. Fertilizer regimes include organic manure (OM), one-half N from organic manure plus one-half N from mineral N fertilizer (1/2OMN), mineral fertilizers [N–phosphorus (P)–potassium (K), NP, NK, PK], and a control. Organic manure (OM and 1/2OMN) significantly increased soil total N and δ15N, which was expected as a great amount of the N applied remained in soils. Mineral NPK fertilizer and mineral NP fertilizer significantly increased total N and slightly increaed δ15N. Phosphorus-deficient fertilization (NK) and N-deficient fertilization (PK) had no effect on soil total N. Significantly greater δ15N was observed in the NK treatment as compared to the control, suggesting that considerable N was lost by ammonia (NH3) voltalization and denitrification in this P-deficiency fertilization regime.

The influence of mineral and bacterial fertilization on the number of fungi in soil under maize

The aim of this study was to evaluate the influence of an application of different rates of mineral fertilizers and their combination with associative N-fixing Klebsiella planticola and Enterobacter spp., and sampling period on the number of fungi in Cambisol and grain yield of maize. The investigation was conducted on Mladenovac experimental station and in the Laboratory of Institute of Soil Science, Belgrade, during 2006. Unfertilized soil was used as the control soil. Each of the studied variants was carried out in three replications. The effect of the studied fertilizers was determined three times during the maize growing season, the number of fungi being determined by indirect dilution method on Czapek nutritive medium. The results of the study showed that all fertilization variants studied influenced, more or less, fungal growth in the study soil. However, the applied high content of mineral nitrogen, phosphorus and potassium, as well as their combination with bacterial inoculants brought about the highest increase in the number of fungi during all studied vegetation periods of maize. The highest increase in the number of soil fungi was registered in the second sampling period. The highest increase in the grain yield of maize was obtained by combined application of microbial inoculants and high rates of mineral NPK fertilizers.

Dependence of soil fertility on organic and mineral fertilization in a 46-year long-term field experiment

Increasing doses of farmyard manure (FYM) or equivalent mineral NPK fertilizers and their combinations were analysed in a crop rotation with potato, maize and winter wheat with special regard to their long-term influence on soil fertility. The yield-increasing capacity of FYM doses was only 82%, as compared to the equivalent amount of mineral NPK. Fairly high N release (50.9 kg ha −1 ) could be observed on the unfertilized plots. Great differences in N utilization were recorded, depending on the form and dose of fertilizers. The average N utilization from FYM was only 29.3%, while that of the equivalent fertilizer application was 49.8%. The lowest soil reactions were observed without fertilization and at the highest NPK doses. Negative N balances generally resulted in low soil organic matter content. FYM and equivalent NPK fertilizers had a similar influence on the ammonium lactate (AL)-extractable K 2 O content of the soil, while an increase in the AL-P 2 O 5 content could be observed in the case of mineral fertilization.

Arbuscular mycorrhizal fungus enhances P acquisition of wheat (Triticum aestivum L.) in a sandy loam soil with long-term inorganic fertilization regime

The P efficiency, crop yield, and response of wheat to arbuscular mycorrhizal fungus (AMF) Glomus caledonium were tested in an experimental field with long-term (19years) fertilizer management. The experiment included five fertilizer treatments: organic amendment (OA), half organic amendment plus half mineral fertilizer (1/2 OM), mineral fertilizer NPK, mineral fertilizer NK, and the control (without fertilization). AMF inoculation responsiveness (MIR) of wheat plants at acquiring P were estimated by comparing plants grown in unsterilized soil inoculated with G. caledonium and in untreated soil containing indigenous AMF. Without AMF inoculation, higher crop yields but lower colonization rates were observed in the NPK and two OA-inputted treatments, and NPK had significantly (P < 0.05) lower impacts on organic C and available P in soils and thereby P acquisition of wheat plants compared with OA and 1/2 OM. G. caledonium inoculation significantly (P < 0.05) increased colonization rates with the NPK and two P-deficient treatments but significantly (P < 0.05) increased vegetative biomass, crop yield, and P acquisition of wheat as well as soil alkaline phosphatase (ALP) activity, only with the NPK treatment. This gave an MIR of ca. 45% on total P acquisition of wheat plants. There were no other remarkable MIRs. It suggested that the MIR is determined by soil available P status, and rational combination of AMF with chemical NPK fertilizer can compensate for organic amendments by improving P-acquisition efficiency in arable soils.

Influence of Cultivars, Plant Spacings, and Mineral NPK Fertilizers Application on Vegetative Growth, Yield and Its Components and Kernels Quality of Sweet Corn (Zea mays var. rugusa, L.)

Influence of Cultivars, Plant Spacings, and Mineral NPK Fertilizers Application on Vegetative Growth, Yield and Its Components and Kernels Quality of Sweet Corn (Zea mays var. rugusa, L.)

Environmental impact of repeated applications of combined paper mill biosolids in silage corn production

Paper mill biosolids (PB) may provide benefits for crop yields and soil nutrients. However, few data are available on metal accumulation and pathogenic populations resulting from applications in silage corn production. A study was initiated to determine the effect of annual spring application of combined PB during 3 consecutive years, with or without calcitic lime, on yield and on the environmental risk posed by N, P, heavy metals (Cu, Zn, Cd, Mo) and Escherichia coli to a silage corn cropped in a loamy sand in eastern Ontario, Canada. Treatments consisted of complete mineral NPK fertilization (PB0), 30 Mg wet weight ha-1 with supplemental N and K, and 60 and 120 Mg wet ha-1 supplemented with K, either with or without 2.5 Mg ha-1 calcitic lime. The PB at 30 Mg wet ha-1 with reduced mineral N and PB at 60 Mg wet ha-1 provided comparable yields to the mineral N fertilization in all years, whereas application of PB at 120 Mg wet ha-1 increased corn yield by 6.0 Mg ha-1 in the third year. After 3 yr, contents of soil NO3-N and the P saturation index (P/Al) were increased, indicating a possible risk of nitrate and P leaching. Lime increased soil pH by 0.8 unit, which in turn caused a large increase in the tissue Mo concentration and Mo uptake by silage corn. The PB, particularly at 120 Mg wet ha-1, produced significant accumulations of Cd and Zn in soil, plant tissue and uptake. The PB showed small counts of E. coli, and consequently very little contamination was observed in the soil and on the harvested crop. Based on these results, the PB used are a good source of nutrients that benefits silage corn yields and represent as well a low risk for human and animal health and for the environment when the application does not exceed 60 Mg wet ha-1 yr-1.Key words: Zea mays L., paper mill biosolids, lime, heavy metals, cadmium, molybdenum, Escherichia coli

Impact of Long-Term Application of Fertilizers on N2O and NO Production Potential in an Intensively Cultivated Sandy Loam Soil

Literature reports on N2O and NO emissions from organic and mineral agricultural soil amended with N-containing fertilizers have reached contradictory conclusions. To understand the influence of organic manure (OM) and chemical fertilizer application on N2O and NO emissions, we conducted laboratory incubation experiments on an agricultural sandy loam soil exposed to different long-term fertilization practices. The fertilizer treatments were initiated in 1989 at the Fengqiu State Key Agro-ecological Experimental Station and included a control without fertilizer (CK), OM, mineral NPK fertilizer (NPK), mineral NP fertilizer (NP), and mineral NK fertilizer (NK). The proportion of N emitted as NO and N2O varied considerably among fertilizer treatments, ranging from 0.83% to 2.50% as NO and from 0.08% to 0.36% as N2O. Cumulative NO emission was highest in the CK treatment after NH 4 + -N was added at a rate of 200 mg N kg−1 soil during the 612-h incubation period, whereas the long-term application of fertilizers significantly reduced NO emission by 54–67%. In contrast, the long-term application of NPK fertilizer and OM significantly enhanced N2O emission by 95.6% and 253%, respectively, compared to CK conditions. The addition of NP fertilizer (no K) significantly reduced N2O emission by 25.5%, whereas applications of NK fertilizer (no P) had no effect. The difference among the N-fertilized treatments was due probably to discrepancies in the N2O production potential of the dominant ammonia-oxidizing bacteria (AOB) species rather than AOB abundance. The ratio of NO/N2O was approximately 24 in the CK treatment, significantly higher than those in the N-fertilized treatments (3–11), and it decreased with increasing N2O production potential in N-fertilized treatments. Our data suggests that the shift in the dominant AOB species might produce reciprocal change in cumulative NO and N2O emissions.

Diversity analysis of nitrite reductase genes (nirS) in black soil under different long-term fertilization conditions

A 30-year fertilizer experiment was conducted to investigate the effects of organic manure and mineral NPK fertilizer on black soil. Four experimental treatments were used: CK, organic manure, mineral NPK fertilizer, and organic manure plus mineral fertilizer. The diversity of the nirS gene was analyzed by PCR-restriction fragment length polymorphism. The Shannon diversity index and Evenness factor, Simpson’s diversity and Shannon-Weiner indices, principal component analysis and a one-way analysis of similarities test showed that organic manure made the opposite contribution to soil diversity of nirS genes compared to mineral fertilizer treatment, which resulted in increased diversity of the nirS gene. Comparison of the phylogenetic analysis of nirS genes in the mineral fertilizer and organic manure clone libraries showed that induction by mineral fertilizer was stronger than that by organic manure, based on the types of unique nirS genotypes found in the two libraries and the evolutionary distances between them.

ASSESSMENT OF ROLE OF SOME COMPOST AND THEIR RESIDUAL EFFECTS ON PLANTS GROWN IN SANDY AND/OR CALCAREOUS SOIL

This work aims to study the role of two composts made of plant residues and added to calcareous soil from Noubaria to clay soil from Kom Osheem; on wheat yields and nutrient status of grains and straw as well as to study their residual effects on the growth of maize, which was grown after wheat. A pot experiment was carried out in earthenware pots filled with 7 kg of the tested soils; at Soils, Water and Environment Research Inst. (SWERI) -Agric. Res. Center (ARC). It was included two soil types; two sources of composted plant residues(C) of wheat straw or banana residues (zero, 5 and 10 ton/fed) as well as NPK mineral fertilizers (M) (zero ,75% and 100% RD).Some treatments of solo , mixed of (C) with (M) as well as no-fertilization (control) were suggested to achieve this study. Wheat (Triticum aestirum) was planted in winter season, till maturity. In the following summer season maize (Zea mays L) was sown, without any new additions, for 70 days only. The obtained results indicated that: Weights of grains and straw of wheat as well as dry weight of whole maize plants were positively responded to manure applications with no–significant differences between the effects of the two used composts in case of wheat and very slight differences in case of maize plants. These responses, to manure applications, were higher in clay soil than that in calcareous one, viz calcareous soil needed to more compost application than clay soil. Application of 10 ton compost /fed associated with 75% RD of NPK mineral fertilizers (10C+75%M) gave the highest weights. N, P, K, Fe, Mn and Zn uptake by wheat components and whole maize plants revealed the same trends mentioned above.

Arbuscular mycorrhizal fungus enhances crop yield and P-uptake of maize ( Zea mays L.): A field case study on a sandy loam soil as affected by long-term P-deficiency fertilization

The P efficiency, crop yield, and response of maize to arbuscular mycorrhizal fungus (AMF) Glomus caledonium were tested in an experimental field with long-term (18-year) fertilizer management. The experiment included five fertilizer treatments: organic amendment (OA), half organic amendment plus half mineral fertilizer (1/2 OM), mineral fertilizer NPK, mineral fertilizer NK, and the control (without fertilization). AMF inoculation responsiveness (MIRs) of plant growth and P-uptake of maize were estimated by comparing plants grown in unsterilized soil inoculated with G. caledonium and in untreated soil containing indigenous AMF. Soil total P, available P, microbial biomass P, alkaline phosphatase activity, plant biomass, crop yield and total P-uptake of maize were all significantly increased ( P < 0.05) by the application of OA, 1/2 OM, and NPK, but not by the application of NK. Specifically, the individual crop yield of maize approached zero in the NK-fertilized soils, as well as in the control soils. All maize plants were colonized by indigenous AMF, and the root colonization at harvest time was not significantly influenced by fertilization. G. caledonium inoculation increased mycorrhizal colonization significantly ( P < 0.05) only with the NK treatment, and produced low but demiurgic crop yield in the control and NK-fertilized soils. Compared to the inoculation in balanced-fertilized soils, G. caledonium inoculation in either the NK-fertilized soils or the control soils had significantly greater ( P < 0.05) impacts on soil alkaline phosphatase activity, stem length, plant biomass, and total P-uptake of maize, indicating that AMF inoculation was likely more efficient in extremely P-limited soils. These results also showed that balanced mineral fertilizers and organic amendments did not differ significantly in their effects on MIRs in these soils.

The effects of mineral fertilizer and organic manure on soil microbial community and diversity

The effects of mineral fertilizer (NPK) and organic manure on phospholipid fatty acid profiles and microbial functional diversity were investigated in a long-term (21-year) fertilizer experiment. The experiment included nine treatments: organic manure (OM), organic manure plus fertilizer NPK (OM + NPK), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), fertilizer N (N), fertilizer P (P), fertilizer K (K), and the control (CK, without fertilization). The original soil was extremely eroded, characterized by low pH and deficiencies of nutrients, particularly N and P. The application of OM and OM + NPK greatly increased crop yields, soil pH, organic C, total N, P and K, available N, P and K content. Crop yields, soil pH, organic C, total N and available N were also clearly increased by the application of mineral NPK fertilizer. The amounts of total PLFAs, bacterial, Gram-negative and actinobacterial PLFAs were highest in the OM + NPK treatment, followed by the OM treatment, whilst least in the N treatment. The amounts of Gram-positive and anaerobic PLFAs were highest in the OM treatment whilst least in the P treatment and the control, respectively. The amounts of aerobic and fungal PLFAs were highest in the NPK treatment whilst least in the N and P treatment, respectively. The average well color development (AWCD) was significantly increased by the application of OM and OM + NPK, and the functional diversity indices including Shannon index (H ′ ), Simpson index (D) and McIntosh index (U) were also significantly increased by the application of OM and OM + NPK. Principal component analysis (PCA) of PLFA profiles and C source utilization patterns were used to describe changes in microbial biomass and metabolic fingerprints from nine fertilizer treatments. The PLFA profiles from OM, OM + NPK, NP and NPK were significantly different from that of CK, N, P, K and NK, and C source utilization patterns from OM and OM + NPK were clearly different from organic manure deficient treatments (CK, N, P, K, NP, NK 6 and NPK). Stepwise multiple regression analysis showed that total N, available P and soil pH significantly affected PLFA profiles and microbial functional diversity. Our results could provide a better understanding of the importance of organic manure plus balanced fertilization with N, P and K in promoting the soil microbial biomass, activity and diversity and thus enhancing crop growth and production.

EFFECT OF BIO-AND MINERAL FERTILIZERS ON GROWTH, YIELD AND TUBER QUALITY OF POTATO PLANTS: 2- YIELD AND TUBER QUALITY

Decreasing NPK dose less than the recommended dose decreased significantly tuber yield [measured as tubers yield (g) per plant, tubers numbers per plant, tubers dry weight per plant and total yield (ton/fed.) as well as its components from protein, ascorbic acid ,starch, N, P ,K, total soluble solids and specific gravity in both studied seasons. In contrast, inoculation of any bacterial strains used induced significantly these parameters and the most effective treatments were found with NFB+PDB+SB followed with NFB+PDB and lastly with SB. The interaction treatments indicate that, plants received mixed three strains of used bacteria plus 50% or 75% NPK (from recommended dose) showed high values regarding yield and its components from crude protein and ascorbic acid , total soluble solids and specific gravity. The level of 75%NPK produced additive effects in this respect. NPK fertilizers at 50% only may be saved if potato tubers were inoculated with non-symbiotic fixing bacteria without serious effects on the tuber yield. Nitrate and nitrite concentrations were decreased significantly with decreasing mineral fertilizers dose in both seasons. Similarly, Nitrate and nitrite levels were decreased significantly when potato tubers inoculated with each of the bio-fertilizers used in comparession with those of uninoculated plants. Inoculation with either mixed strains of used bacteria or NFP+PDB gave the highest reduction in the levels of both nitrate and nitrite in potato tuber. Plants received 50% or 75% NPK (from recommended dose) produced the highest reduction in nitrate and nitrite levels compared with the control (100% recommended dose of NPK) while, the lowest reduction of both nitrate and nitrite were detected in tubers produced from plants inoculated with NFB. Decreasing NPK dose, overall bio-fertilizers used, decreased the percentages of reducing sugars, insoluble carbohydrates and total carbohydrates whereas increased non-reducing sugars and total sugars in potato tubers during the two growing seasons. Bio-fertilizers application alone significantly decreased reducing sugars and total sugars whereas increased non-reducing sugars, insoluble carbohydrates and total carbohydrates percentages in the tubers of potato plants inoculated with each of the three bacterial strains used in comparison to those of uninoculated one. The most effective treatments was found with NFB+PDB+SB.Again, NFB strain was more effective than PDB followedwith SB. The interaction treatments, show that bio-fertilizers significantly decreased reducing sugars and total sugarswhereas increased non-reducing sugars, insoluble carbohydrates and total carbohydrates percentages in potato tubers of plants grown under any dose of NPK used in comparison to the corresponding control (uninoculated). Again, the best treatment was found with NFB+PDB+SB. Plants received only half the dose of the recommended NPK fertilizers together with the dual inoculation recorded considered increases in non-reducing sugars, insoluble carbohydrates and total carbohydrates in the tubers whereas, decreased that of reducing sugars and total sugars percentages. It could be concluded that the use of only bio-fertilizers for the production of potatoes is insufficient, so, they must be used together with mineral NPK fertilizers. Adding bio-fertilizers (naimly, Azospirillum brasilense , Psuedomonas fluerences and Bacillus circulance) to 50% of the mineral NPK fertilizers from the recommended dose (90 kg N + 37.5 kg P2O5 + 48 kg K2O/fed.) exhibited resistance of potato grown against NPK stress and induced its yield. The recommendation may reduce the extensive use of mineral fertilizers (about 50%) without affecting on potato productivity productivity. In addition the reduction of 50% from the mineral NPK fertilizers used might help for reducing the production cost as well as diminishing the environmental pollution and minimizing the harmful effects of using chemical fertilizers on human health.

EFFECTS OF COMPOST AND BIOFERTILIZERS ON PRODUCTIVITY OF CANOLA PLANTS

The present investigation was conducted to investigate the effects of biological and organic fertilization including cerealine, mycorrhizae and compost on growth, yield and oil percentage of canola plants grown under two levels of NPK mineral fertilizers, i.e. 50 and 100% of the recommended NPK. The experiments were carried out in the plastic green house of the Plant Physiology Division, Fac. of Agric., CairoUniv., Giza, Egypt, during two successive growing seasons; 2004-2005 and 2005-2006. The obtained results confirmed the positive effects of bio and organic fertilization on growth and yield of canola plants either under half or full NPK dose which recorded significant increments in comparison with only mineral fertilized plants. In addition, the treated plants with the combination of half NPK+ compost+ cerealine+ mycorrhizae were able to approach their optimal productivity under only full NPK. Moreover, the percentage of oil was increased in seeds of canola plants treated with the half NPK + the combinations of compost, compost+ cerealine, compost+ mycorrhizae and compost+ cerealine+ mycorrhizae in comparison with the control plants of full NPK treatment. Furthermore, the value of seed oil content (gplant) of half NPK+ compost+ cerealine+ mycorrhizae was exceeded the comparable value of the control plants of full NPK. Therefore, these results strongly suggest that it could be reduce the amount of NPK mineral fertilizers to the half dose to achieve the same yield of canola plants treated with full NPK dose when compost and bio fertilizers were added, leading to economical and environmental benefits through reducing the cost and the hazardous effects of mineral fertilizers on the environment.

Long-term manure and fertilizer effects on soil organic matter fractions and microbes under a wheat–maize cropping system in northern China

As an essential indicator of soil quality, soil organic carbon (SOC) and its different labile fractions have an important role in determining soil chemical, physical, and biological properties. The objective of this study was to evaluate the soil carbon (C) and nitrogen (N) contents in different soil organic matter (SOM) pools (light and heavy fractions), the role of light- and heavy-fraction C in SOC sequestration, and culturable microbial counts in the surface (0–20 cm) of a fluvo-aquic soil after 18 years of fertilization treatments under a wheat–maize cropping system in the North China Plain. The experiment included seven treatments: (1) OM, organic manure; (2) 1/2OMN, half organic manure with mineral fertilizer NPK; (3) NPK, mineral fertilizer NPK; (4) NP, mineral fertilizer NP; (5) PK, mineral fertilizer PK; (6) NK, mineral fertilizer NK; and (7) CK, unfertilized control. Carbon and N contents of the light and heavy fractions were highest in the OM treatment, while the CK treatment showed the lowest value. Application of half organic manure with mineral fertilizer NPK (treatment 2) significantly increased C and N contents of the light and heavy fractions in soil in comparison with application of mineral fertilizer alone (treatments 3, 4, 5, and 6). For the mineral fertilizer treatments, a balanced application of NPK (treatment 3) showed higher C and N contents of the light and heavy fractions than an unbalanced use of fertilizers (treatments 4, 5, and 6). Heavy-fraction C dominated total SOC storage in all treatments. The total SOC increase under fertilization treatments is attributed to an increase in C content of both the light and the heavy fraction. However, the SOC increase for the manure treatments was mainly due to an increase in the C content of the heavy fraction, whereas that for mineral fertilizer treatments was mainly due to an increase in the C content of the light fraction. The total soil culturable microbial counts (including bacteria, fungi, and actinomycetes) was observed to be highest for the OM treatment, while the control plot showed the lowest value. Application of half organic manure with mineral fertilizer NPK was found to produce a higher culturable microbial counts than application of mineral fertilizers alone, and the NPK treatment gave a higher culturable microbial counts than other mineral fertilizer treatments (NP, PK or NK). Light-fraction C is probably the better predictor of microbial abundance, as it correlated more strongly with culturable microbial counts than total SOC did.