Addition Of Organic Manure Research Articles

Long-term effects of organic manure and inorganic fertilization on sustainability and chemical soil quality indicators of soybean-wheat cropping system in the Indian mid-Himalayas

A long-term field study was commenced in 1995-96 to assess the impact of continuous application of inorganic fertilizers and organic manure on sustainability, productivity and chemical indicators of soil quality in an irrigated soybean-wheat cropping system (SWCS). Six treatments comprised inorganic fertilizers (NPK) and manure (M) either alone or in combination. Soybean yield indicated declining trend −22.50, −56.0 and −25.0 kg ha−1 year−1 under unfertilized control, sole nitrogen and NPK treatments, respectively while addition of organic manure resulted in a positive yield trend. Plot receiving NPK had positive yield trend of 118 kg ha−1 year−1 in wheat crop. The highest positive yield trend was obtained with manure (M) and NPK treatment, values being 17.60 and 191 kg ha−1 year−1 in soybean and wheat, respectively. Significantly (p < 0.05) the highest grain yield was also observed under the MNPK treatment, soybean and wheat reporting 2.56 and 4.31 Mg ha−1, respectively which was ∼ 30 and 25% higher than NPK treatment, respectively. Significantly higher yield sustainability was observed in the plots receiving manure either alone (0.77 and 0.51) or in combination with N fertilizer (0.79 and 0.79) or with NPK, MNPK (0.89 and 0.92) compared to the treatment, which did not receive the manure in both soybean and wheat crops. Due to continuous cropping and fertilization over the years, available N increased from initial values in all the plots except CK (−3.89 and −3.59%) under 0–15 and 15–30 cm soil depths. Negative trends for available P were observed in all treatments except MNPK over the years of continuous cropping. A significantly decreasing trend for the available K was observed under CK, N, NPK and M treatments, whereas a significant accumulation was estimated under MN and MNPK treated plots in both soil depths. Significantly higher accumulation of available N, P and K were observed under MNPK treatment compared to the rest of the treatments. The treatment MNPK had the highest soil DTPA-extractable Fe, Mn, Zn and Cu after 21-years of cropping and fertilization. The sustainable yield index (SYI) values indicated that soybean yield was more sustainable compared to the wheat. The SYI and grain yield of soybean had significantly higher correlation with available N, P, Fe, Mn, Zn and Cu. Soil available N had significantly higher values of coefficient of regression (r2) for wheat (0.98; p = 0.001 and 0.97; p = 0.001) compared to soybean (0.74; p = 0.029 and 0.74; p = 0.027) under 0–15 and 15–30 cm soil depths, respectively. The SYI was strongly positively correlated with chemical indicators of soil quality. Hence, SYI could potentially be used for assessment of agricultural productivity and soil sustainability elsewhere.

Effect of Integrated Nutrition in Aromatic Rice on Carbon and Nutrient Status in an Inceptisol

ABSTRACTInorganic fertilizer-based nutrient management is the maintenance of soil fertility for sustaining increased crop productivity, but often at the cost of degrading soil health. This study was conducted to determine whether incorporation of organics in the conventional inorganic-based nutrient management practice on aromatic rice could sustain both fertility and soil organic carbon status on a silt loam Aeric Haplaquept. Addition of organic manure along with inorganic fertilizer could almost maintain organic carbon status of soil, while the treatment only with inorganic fertilizer registered a substantial decrease (6.58%) from its initial value. Among the treatment combinations, the treatment receiving 1 t ha−1 mustard cake and inorganic fertilizer @ N40P20K20 was the best, which registered the highest grain (3.01 t ha−1) and straw (5.32 t ha−1) yield of rice, highest nutrient uptake, and least decline in available N, P, and K status of soil. However, even the best treatment combination also was proved to be suboptimal in sustaining soil fertility.

Degraded lands and their management for rehabilitation and improving crop productivity

Soil degradation causes decline in its productivity, deterioration in vegetative cover, qualitative, and quantitative decline of soil and water resources and pollution of air is widespread in India. In recent decades, the problem is greatly aggravated because of country’s increasing population, requiring marginal areas to be brought under the cultivation to meet the growing food demand. Poverty and natural resources degradation forced individuals to search for more land for food, fodder and fibre production. The main causes of degradation due to direct/indirect human intervention are deforestation and removal of natural vegetation, overgrazing, and converting forest lands to arable land, cultivating steep slopes and degrading marginal lands, other agriculture related activities and over exploitation of the vegetation for domestic purposes. Similarly, the removal or in-situ burning of crop residues, minimum addition of organic manures, and intensive cultivation are the major causes of the depletion of soil organic carbon (SOC). Potential threats to the conservation of soil resources are soil erosion both by water and air, salinization/ alkalinity, acidity, organic carbon (OC) losses, nutrient imbalance, pollution/contamination by toxic substances, and soil sealing and capping. To arrest the process of degradation, urgent measures viz., indigenous soil and land conservation practices, conservation farming, watershed management including land and water management technology, water harvesting, Integrated plant nutrient supply, (IPNS), physical, mechanical, and biological approach, soil amendments, restoration of SOC, aforestation and agro-forestry, farming system approach, and organic farming, etc. are required for rehabilitating productivity of degraded soils so that more food could be produced to provide livelihood and environmental security to the ever increasing Indian population.

Inorganic Fertilization Effects on the Structure of a Calcareous Silt Loam Soil

Core Ideas Long‐term inorganic fertilization decreased aggregate stability. Long‐term inorganic fertilization decreased soil macroporosity. Long‐term inorganic fertilization did not change soil organic C content. Soil water‐holding capacity was not affected by inorganic fertilization. Swine manure combined with inorganic fertilizers improved soil structure. Inorganic fertilizers have been intensely used in the North China Plain (NCP) to maintain or increase crop yields, but their effects on soil physical properties, especially soil structure, are unclear. The objective of this study was to evaluate the effects of 12 yr of successive application of inorganic fertilization on soil aggregate stability, pore structure, and hydraulic properties of a calcareous silt loam soil. A long‐term field experiment (2001–2013) was established at Luancheng Ecosystem Station, NCP. The experiment included three fertilization treatments: (i) inorganic fertilizer, NPK; (ii) inorganic fertilizer and organic manure, NPKOM; and (iii) a control treatment with no fertilizer, CK. Results showed plots receiving long‐term NPK and NPKOM had significantly greater wheat (Triticum aestivum L.) (275 and 307%, respectively) and maize (Zea mays L.) yields (59 and 107%, respectively) than the control. However, the application of inorganic fertilizer significantly decreased aggregate stability and macroporosity, by 55.3 and 36.1%, respectively, relative to the control. No differences in soil organic carbon (SOC), bulk density (BD), saturated conductivity (Ks), and water‐holding capacity were found between the NPK and the CK treatments. On the other hand, the addition of organic manure with inorganic fertilizers increased SOC, total porosity, and saturated conductivity by 38.5, 5.2, and 75%, respectively, compared with the CK treatment. This study indicated inorganic fertilization alone could not improve soil structure of the calcareous silt loam, although it maintained high yields. Use of organic amendments along with inorganic fertilizers can improve soil structure and crop yields.

Soil labile organic carbon fractions and soil organic carbon stocks as affected by long-term organic and mineral fertilization regimes in the North China Plain

To improve C sequestration in soils and mitigate climate change, it is essential to understand how nutrient management strategies impact on soil organic carbon (SOC) stocks and labile fractions. This study was designed to explore changes in soil bulk density (BD), SOC concentrations, SOC stocks and soil labile organic C fractions (mineralizableC (Cmin), microbial biomass C (MBC), dissolved organic C (DOC), particulate organic C (POC), light fraction organic C (LFOC) and permanganate oxidizable C (KMnO4-C)) under 26-year fertilization regimes in a wheat-maize rotation system in the North China Plain. Soil from the following six treatments was analyzed: (1) Control with no amendment addition (CK); (2) Standard rate of mineral fertilizer treatment (SMF) reflecting local farmers' practice; (3) Standard rate of organic manure treatment (SMA) with total N input equal to SMF; (4) Half the standard rate of mineral fertilizer plus half the standard rate of organic manure treatment (1/2 SMF+1/2 SMA); (5) Double standard rate of mineral fertilizer treatment (DMF); (6) Double standard rate of organic manure treatment (DMA). Results showed that all long-term fertilization regimes significantly decreased BD in topsoil compared to CK except for SMF, with treatments that included organic manure resulting in the lowest BDs. Treatments that included organic manure had significantly higher SOC concentrations and stocks than mineral or unfertilized treatments. The organic manure treatments also had higher concentrations of non-labile C but at the same time a higher proportion of labile C than the mineral or unfertilized treatments. This was confirmed by the carbon management index (CMI) which was significantly increased by organic manure addition. Control and mineral fertilized treatments had higher efficiencies of C retention (RE) from added inputs (crop residues only). Differences in Cmin, POC and KMnO4-C were affected by differences in MA-C, however, changes in rhizodeposition-C, stubble-C and root-C significantly affected DOC, MBC and LFOC. This study demonstrates that fertilization strategies that include organic manure can increase the pool of stable C in the surface soil layer, while at the same time increasing concentrations and proportions of labile C. Organic manure use can therefore contribute to improved nutrient cycling services and higher soil quality in the North China Plain.

Effect of organic manure on Cd and As accumulation in brown rice and grain yield in Cd-As-contaminated paddy fields.

Large areas of paddy fields in mining areas in south China have been contaminated by mixed Cd and As. To test the possibility of using organic manure (OM) as a method of reducing Cd and As accumulation in brown rice and increase the grain yield in such paddy fields, two rice cultivars [Jianyou G2 (JY) and Fengyousimiao (FY)] and three amounts of OM (0, 0.5, 1.5kg/m2) were examined in three Cd-As-contaminated paddy fields (Fogang, Dabaoshan, Fankou) in Guangdong Province. The results show that the application of OM can effectively increase the grain yield and reduce Cd. However, the As concentration was found to increase in brown rice, especially when high levels of OM were used. The addition of OM increased the soil pH and organic matter content in the soils and enhanced the activities of superoxide dismutase (SOD) and catalase (CAT) in plant tissues. Our results suggest that OM can be used as an amendment to effectively decrease Cd accumulation in brown rice in Cd-contaminated paddy fields. However, it is necessary to consider the negative effects of OM amendments when adding OM to As-contaminated paddy fields.

Long term application of herbicides on soil microbial demography in rice rice cropping sequence of North-East India

Field study was carried out to determine the long term effect of herbicide application on soil microbial community in rice-rice cropping sequence in acid soil of North-East India. Treatment comprised of absolute control with one hand weeding, butachlor + 2, 4-D with 100% NPK through chemical fertilizer, butachlor + 2, 4-D with 75% NPK through chemical fertilizer and 25% through organic source, butachlor + 2, 4-D rotated with pretilachlor with 100% NPK through chemical fertilizer and butachlor + 2, 4-D rotated with pretilachlor with 75% NPK through chemical fertilizer 25% through organic source. Result revealed that, after 14 years of continuous use of herbicide and organic input along with recommended dose of fertilizer application demonstrated significant increase in the activity of acid phosphatase. The effect of herbicide application was more prominent with sole chemical fertilizer than with organic manure for 25% N fertilizer replacement. Dehydrogenase activity in soil was increased following herbicide application up to 14 days after that it again decreased more prominent with addition of organic manure than with chemical fertilizer. No characteristic trend of urease activity was observed after application of herbicide. Significant inhibition of respiration was observed after application of herbicide up to 14 days followed by gradual recovery afterwards. Microbial biomass carbon in soil was significantly enhanced by application of organic manure for 25% N fertilizer substitution. Under rice-rice cropping system, application of herbicide showed temporary decline in microbial population and enzyme activities up to 14 days. Application of organic manure for 25% N fertilizer substitution significantly enhanced the microbial population and enzyme activities as compared to sole application of chemical fertilizers. Further application of butachlor rotated with pretilachlor resulted in higher microbial population as well as enzyme activities.

Nutrient removal through plant components of low yielding coconut plantation

The potential production ofdifferent lands varies depending on the quality of the.land. The land suitability class S4; moderately suitable and S5; marginally suitable lands yielding 5,000 to 10,000 nuts ha–1 yr–1 and 2,500 to 5,000 nuts ha–1 yr–1 for coconut respectively are regarded as low potential productivity lands. These lands have limitations which are moderately severe and reduce the level of coconut productivity. Thus, these lands require inputs like fertilizer and agricultural practices like contour drains or terracing, husk pits, cover crops and mulch around the palms to break even cost and bring about profit to moderate level. Fertlizer application is one of the important inputs for such lands. The information on macro and micronutrient removal by Typica x Typica (CRI 60) coconut palms and required fertilizer input to compensate the loss of nutrients in low potential productivity lands are not available. Therefore, the objective of this study was to estimate the macro and micronutrient removal by coconut palms in low yielding lands and to compare nutrient removal with fertilizer inputs and soil reserves.Harvested nuts, fallen fronds and fallen inflorescences were collected monthly interval for three years from ten coconut palms of Typica x Typica (CRI 60) grown on moderately suitable Boralu series soil (Red Yellow Podzolic). The macro and micronutrients in plant components and nutrient reserves in experimental site were determined. The results reavealed that the major nutrient removed by all plant parts were 164,53,37; 22,19 and 9.85 kg–1 ha–1 yr–1 for K, N, Na, Ca, Mg and P respectively. The amount of N, P, K, Ca and Mg applied annually as fertilizers were 58, 11.5, 125.9,69.9 and 19 kg–1 ha–1 respectively. Except K and Mg, the other macronutrients, input by application of fertilizer slightly exceeds the nutrient removal. The N, P, Ca and Mg reserves of soil was high and would not deplete rapidly. The K input by application of 3.3 kg of APM fertilizer mixture was about 76.7 % of the K removal. This leads to depletion of exchangeable K pool rapidly, if the harvested nuts and fallen plant components are all removed from the plantation. Hence, the depletion should be compensated for either by adding extra 80 kg ha–1 of Muriate of Potash or recycling of fallen fronds and residues of the inflorescences or mulching the manure circle using fresh coconut husks or addition of organic manure.The mironutrient removed through all plant parts were 0.93, 0.53, 0.28, 0.15 and 0.09 kg–1 ha–1 yr–1 for Fe, Mn, Zn, B and Cu respectively. The reserves of available Fe, Mn, Cu and Zn in Boralu series soil was very high and the gap between the soil reserves and the plant removal rates were high. Hence, micronutrient containing fertilizers would not be required as the depletion of micronutrient reserves in soil would not occurre significantly.

Use of biological indicators of soil health to estimate reactive nitrogen dynamics in long-term organic vegetable and pasture systems

Diverse crop rotations, cover crops and the possibility of integrating livestock make organic systems potentially more sustainable than other agroecosystems. Lower reactive nitrogen (N) in organic systems minimizes the potential for N losses. However, addition of organic manures and residues containing mineralizable N and carbon (C) have the potential to enhance nitrous oxide (N2O) emissions. We conducted a 39 d laboratory incubation to assess key microbiological drivers controlling nitrification and denitrification in long-term organic agroecosystems during simulated freeze-thaw cycles. Soils were collected from two annual organic vegetable systems receiving 1) mixed-compost, or 2) broiler litter and 3) an organic perennial pasture system cropped to vegetables every third year. Soil microcosms amended with 15N labelled sugar beet residue or unamended were maintained at 40, 60 and 80% of water filled pore space (WFPS). Significant N2O was emitted (4287–6138 μg kg−1soil) via denitrification from amended soil microcosms at 3 °C and 80% WFPS. Archaeal (AOA) and bacterial (AOB) nitrifier amoA gene copies were affected by temperature and reactive N species during freeze-thaws. Long-term organic vegetable cropping systems receiving mixed-compost additions had the potential to accumulate C and immobilize excess reactive soil N (particularly nitrates) thereby improving soil health and reducing N2O emissions.

Microbial Functional Diversity, Biomass and Activity as Affected by Soil Surface Mulching in a Semiarid Farmland.

Mulching is widely used to increase crop yield in semiarid regions in northwestern China, but little is known about the effect of different mulching systems on the microbial properties of the soil, which play an important role in agroecosystemic functioning and nutrient cycling. Based on a 4-year spring maize (Zea mays L.) field experiment at Changwu Agricultural and Ecological Experimental Station, Shaanxi, we evaluated the responses of soil microbial activity and crop to various management systems. The treatments were NMC (no mulching with inorganic N fertilizer), GMC (gravel mulching with inorganic N fertilizer), FMC (plastic-film mulching with inorganic N fertilizer) and FMO (plastic-film mulching with inorganic N fertilizer and organic manure addition). The results showed that the FMO soil had the highest contents of microbial biomass carbon and nitrogen, dehydrogenase activity, microbial activity and Shannon diversity index. The relative use of carbohydrates and amino acids by microbes was highest in the FMO soil, whereas the relative use of polymers, phenolic compounds and amines was highest in the soil in the NMC soil. Compared with the NMC, an increased but no significant trend of biomass production and nitrogen accumulation was observed under the GMC treatment. The FMC and FMO led a greater increase in biomass production than GMC and NMC. Compare with the NMC treatment, FMC increased grain yield, maize biomass and nitrogen accumulation by 62.2, 62.9 and 86.2%, but no significant difference was found between the FMO and FMC treatments. Some soil biological properties, i.e. microbial biomass carbon, microbial biomass nitrogen, being sensitive to the mulching and organic fertilizer, were significant correlated with yield and nitrogen availability. Film mulching over gravel mulching can serve as an effective measure for crop production and nutrient cycling, and plus organic fertilization additions may thus have improvements in the biological quality of the soil and its sustainability in the rainfall-limited semiarid region.

Growth and Yield of Rice (Oryza sativa L.) on various planting pattern and addition of organic fertilizers

The aim of this study is to examine the effect of planting pattern and organic fertilizers to growth and yield ofrice (Oryza sativa L.). The research was carried out at January - May 2015 in Toyaning Village, Rejoso Regency, Pasuruan, 2 m above the sea level with alluvial soil type and an average temperature of 22oC-31oC. Research applied with Random Group Design with six treatments: conventional Planting move (Tapin) without organic manure, Jajar legowo (JA) without organic manure, SRI without organic manure (SA), conventional Planting move with organic manure (TO), Jajar legowo with organic manure (JO), SRI with organic manure (SO). The results showed the pattern jajar legowo give best expression plant heigh, the dry weight of the plant top at age 14 day after plant (HST), grain weights/compartments, and net weighted/acres. Conventional planting move gives better response on the dry weight of the plant top at 50 HST, and dry weights bottom plant at 14 HST. The SRI planting pattern give best response number of saplings and the number of saplings of productive/clump, grain weight/clump, and weight of 1000 grain. The treatment of planting pattern with the addition of organic manure gives higher yields rather than without organic manure. Yield of Jajar Legowo is 10.2 tons/ha, highest than other 10.1 2 ton/ ha for Tapin and 68.05 ton/ha for SRI

The Influence of Continuous Organic Manure Application on Chemical Properties and Organic Carbon of Cultivated Soils

A study was conducted to determine the effects of short- and long-term application of organic manure on soil chemical properties including soil pH, EC, CaCO3, SOC, and soil available N and P under arid conditions. The solid and liquid organic manure were applied to the soils cropped with the vegetable for either up to 2-years under vegetable plants or 15-years to soils cropped with fruit trees. Soil samples were collected at sampling depths of 0-15, 15-30, 30-45, 45-60 cm. Results showed that the soil organic carbon (SOC) content ranged between 0.6-12 g kg-1 and 1.7-31.5 g kg-1 after organic manure application for one year and 15-years in soil samples cropped with fruit trees, respectively. Moreover, SOC content ranged between 0.6 and 6.4 g kg-1 and 0.9 and 8.6 g kg-1 after organic manure application for the one year and 2-years in soil samples cropped with vegetable, respectively. The highest soil available N (211 mg kg-1) was found after long term application of organic manure (15-years) followed by that (162 mg kg-1) found after the 2-years organic manure application. The higher soil available P (52-60.2 mg kg-1) was also found with 15-years and 2-years application of organic manure. It could be concluded that the addition of organic manure to the soil of arid condition may be suitable for maintaining soil organic carbon and improving soil fertility by increasing N and P availability.

Higher rates of manure application lead to greater accumulation of both fungal and bacterial residues in macroaggregates of a clay soil

Microbial residues represent a significant soil organic matter pool and participate in soil aggregation. The addition of organic manure is known to modify soil aggregation and strongly influence soil microbial residues. How manure application influences the spatial distribution of microbial residues in soil aggregates is largely unknown. This study attempts to determine the effect of manure application at various rates on the content and distribution of microbial residues among aggregates of different sizes. We used a long-term manure application experiment in a Mollisol in northeastern China, where manure has been applied since 2001 at rates of 0, 7.5, 15, and 22.5 Mg ha−1 yr−1 (dry weight). The abundance of microbial residues was indicated by amino sugar analysis. Glucosamine and muramic acid were used as biomarkers for fungal and bacterial residues, respectively. Amino sugars were examined within four aggregate fractions: large macroaggregate (>2000 μm), small macroaggregate (250–2000 μm), large microaggregate (53–250 μm) and small microaggregate (<53 μm). Application of manure at 15 and 22.5 Mg ha−1 yr−1 provided significantly higher proportions of macroaggregates and mean weight diameter (MWD) than non-manure treatment and manure applied at 7.5 Mg ha−1 yr−1. Manure application, especially at higher rates, significantly stimulated the accumulation of total amino sugars in both macroaggregates and large microaggregates and more amino sugars were found in >250 μm macroaggregates compared with microaggregates. However, effects of manure application rates on amino sugar accumulation in larger aggregates were limited when manure rate was increased from 15 to 22.5 Mg ha−1 yr−1. The response of fungal- and bacterial-derived amino sugars to manure application rates differed among aggregate fractions, i.e., glucosamine associated with macroaggregates increased more than that of microaggregates, whereas the enhancement of muramic acid was prominent in both macroaggregates and large microaggregates. The mass proportions of macroaggregates and MWD showed significant positive correlations with amino sugar contents, indicating that these microbial residues are involved in the formation and stabilization of aggregates. Manure applications greatly increased the contribution of microbial residues to soil organic C (SOC) in small macroaggregates and large microaggregates (P ≤ 0.05). We conclude that higher manure input may promote soil aggregation and higher SOC storage, which is closely related to a greater microbial residues-mediated improvement of soil aggregate stability. Our results also suggest that measurement of amino sugar content is a useful approach to assess fungal and bacterial contributions to soil aggregation.

Effect of integrated nutrient management on physico-chemical parameters of soil in rice-wheat system

A field experiment was conducted to assess the effects of combined application of organic manure through biogas slurry in the form of bio gas slurry (BGS) and inorganic NPK fertilizers on soil physico-chemical properties of soil in rice, wheat or stevia. Laboratory analysis on the soil samples collected (October 2013) from an on-going long-term field experiment (in progress since Kharif 2009–10) was made. The organic manure through BGS @ 6 t ha−1 was incorporated along with nitrogen fertilizer (N @ 80 and 120 kg ha−1), phosphorus fertilizer (P @ 30 kg ha−1) and potassium fertilizer (K @ 30 kg ha−1) to the rice crop. In the wheat crop, nitrogen fertilizer (N @ 120 kg ha−1), phosphorus fertilizer (P @ 0, 30 and 60 kg ha−1) and potassium fertilizer (K @ 30 kg ha−1) were applied without addition of organic manure. Results showed that the application of organic manure through BGS along with inorganic fertilizers decreased the soil pH and electrical conductivity (EC), whereas, the increased content of soil organic carbon (OC), available nitrogen (N), phosphorus (P) and potassium (K) was found in these treatments. On the other hand, among the physical properties, the bulk density (Db) and particle density (Dp) were found to decrease, whereas the water holding capacity (WHC) and porosity increased with the addition of organic manure along with chemical fertilizers under rice-wheat system.

Nitrogen Release Pattern From Organic Manures Applied to an Acid Soil

Study of nitrogen release pattern from organic manures is very essential to ensure nitrogen supply in adequate quantity and at proper time to crop plants in an acid soil. A laboratory incubation experiment was conducted to determine the nitrogen release pattern from vermicompost (V.C), poultry manure (P.M), neem, inorganic fertilizer (I.O) and its combinations applied to an acid soil at two different rates. Cumulative nitrogen mineralization was significantly higher throughout the incubation period for I.O, V.C+P.M and I.O+V.C while it was two weeks after incubation for V.C and V.C+Neem due to the inhibitory effect of neem on nitrification. The results indicated a significant increase in the rate of N mineralization in the first one week in which the highest rate of 3.36 mg N day-1 was observed for inorganic fertilizer and thereafter it slowed down. V.C followed by V.C+Neem recorded higher rate of N mineralization of 0.24 and 0.23 mg day-1 respectively, from 48th days after incubation. V.C+Neem at 120 kg N equivalent ha-1 recorded the highest ammonia content of 42.1% to total available N while V.C+P.M recorded higher nitrate content of 82.3% at the end of the incubation period. Positive correlation between initial nitrogen and total mineralized N from the manures and fertilizers (R2 = 0.563) was observed. Furthermore, addition of organic manures resulted in increase in soil pH where as inorganic fertilizer showed a slight decrease (5.73) than control (5.78).

Diversity of cultivable Azotobacter in the semi-arid alfisol receiving long-term organic and inorganic nutrient amendments

Monitoring the biological processes and microbial diversity is essential for sustaining the soil health for long-term productivity. In the present study, the impact of long-term nutrient management systems on changes in Azotobacter diversity of Indian semi-arid alfisol was assessed. Three soils, i.e., unfertilized control, soils amended with organic manures (OM), and with inorganic chemical fertilizers (IC) from century-old experimental fields were evaluated for Azotobacter diversity by Amplified Ribosomal DNA Restriction Analysis (ARDRA). Bray–Curtis’s similarity index of the ARDRA data of the isolates was analyzed by non-metric multi-dimensional scaling and hierarchical cluster analysis. The results revealed that the long-term organically managed soil recorded significantly higher soil organic carbon, microbial biomass carbon, and total culturable bacterial counts, whereas the chemical fertilized and control soils remained unaffected. Though the Azotobacter population was significantly higher in OM soil than IC and control soils, the genetic diversity was unaffected due to long-term addition of either organic manures or inorganic chemical fertilizers. This result implies the importance of continuous addition of organic manures and also the optimal use of inorganic chemical fertilizers without disturbing the biological properties of the soil.

Effect of Induced Soil Compaction on Changes in Soil Properties and Wheat Productivity under Sandy Loam and Sandy Clay Loam Soils: A Greenhouse Experiment

The continuous use of heavy machinery and vehicular traffic on agricultural land led to an increase in soil compaction, which reduces crop yield and deteriorates the physical conditions of the soil. A pot experiment was conducted under greenhouse conditions to study the effects of induced soil compaction on growth and yield of two wheat (Triticum aestivum) varieties grown under two different soil textures, sandy loam and sandy clay loam. Three compaction levels [C0, C1, and C2 (0, 10 and 20 beatings)], two textural classes (sandy loam and sandy clay loam), and two genotypes of wheat were selected for the experiment. Results indicated that induced soil compaction adversely affected the bulk density (BD) and total porosity of soil in both sandy loam and sandy clay loam soils. Compaction progressively increased soil BD from 1.19 Mg m−3 in the control to 1.27 Mg m−3 in C1 and 1.40 Mg m−3 in C2 in sandy loam soil while the corresponding increase in BD in sandy clay loam was 1.56 Mg m−3 in C1 and 1.73 Mg m−3 in C2 compared to 1.24 Mg m−3 in the control. On the other hand, compaction tended to decrease total porosity of soil. In case of sandy loam, porosity declined by 5% and 17% in C1 and C2, respectively, and declined in sandy clay loam by 29% and 54%, respectively. Averaged over genotypes and textures, shoot length decreased by 15% and 26% at C1 and C2, respectively, and straw yield decreased by 21% and 61%, respectively. The compaction levels C1 and C2 significantly decreased grain yield by 12% and 41%, respectively, over the control. The deleterious effect of compaction was more pronounced on root elongation and root mass, and compaction levels C1 and C2 decreased root length by 47% and 95% and root mass by 41% and 114%, respectively, over the control. Response of soil texture to compaction was significant for almost all the parameters, and the detrimental effects of soil compaction were greater in sandy clay loam compared to sandy loam soil. The results from the experiment revealed that soil compaction adversely affected soil physical conditions, thereby restricting the root growth, which in turn may affect the whole plant growth and grain yield. Therefore, appropriate measures to avoid damaging effects of compaction on soil physical conditions should be practiced. These measures may include soil management by periodic chiseling, controlled traffic, conservation tillage, addition of organic manures, and incorporating crops with deep tap root systems in a rotation cycle.

Rhizospheric Flora and the Influence of Agronomic Practices on Them: A Review

Plants and most of the microorganisms in the rhizosphere have symbiotic relationships. While rhizodeposits (root exudates having lysates, mucilages) provide the food and influence the structure and number of microorganisms in the rhizosphere, the latter benefit the plants through secretion of a number of growth promoting hormones, organic acids and siderophores that help in increased availability and uptake of nutrients by plants. The interactions of roots and microflora may influence the plant growth positively through a variety of mechanisms, including fixation of atmospheric nitrogen by different classes of proteobacteria, increased biotic and abiotic stress tolerance imparted by the presence of endophytic microbes, and direct and indirect advantages imparted by plant growth-promoting rhizobacteria. The soil microorganisms affect plant growth, and are affected by plant growth, but there is incomplete understanding of their cumulative and interactive effects on plant performance, especially under varied crop production regimes. The diversity of cropping systems in both time and space (by rotations, intercropping, and so on) creates a mosaic of soil resources and niches, which in turn, enhances belowground biodiversity and improves the resilience of the system as a whole. Therefore, agronomic practices such as crop rotation, tillage, addition of organic manures, chemical fertilizers and mulches influence the structure and number of microorganisms in the rhizosphere. However, very little data are available on this subject. There is a need to generate such data to develop a strategy for sustainable agriculture.

Contrasting soil microbial responses to fertilization and tillage systems in canola rhizosphere

Information regarding the simultaneous evaluation of tillage and fertilization on the soil biological traits in canola production is not available. Therefore, field experiments were conducted in 2007–2010 in a split plot based on randomized complete block design with three replications. Main plots consisted of conventional tillage (CT); minimum tillage (MT) and no tillage (NT). Six strategies of fertilization including (N1): farmyard manure (cattle manure); (N2): compost; (N3): chemical fertilizers; (N4): farmyard manure+compost; (N5): farmyard manure+compost+chemical fertilizers and (N6): control, were arranged in sub plots. Results showed that the addition of organic manure increased the soil microbial biomass. No tillage system increased microbial biomass compared to other tillage systems. The activities of all enzymes were generally higher in the N4 treatment. The activity of phosphatase and urease tended to be higher in the no tillage treatment compared to the CT and MT treatments.

Changes in soil organic carbon pools after 10 years of continuous manuring combined with chemical fertilizer in a Mollisol in China

It is still unclear that whether substantial amounts of organic manure amendment could increase soil organic carbon (SOC) sequestration in a Chinese Mollisol with relatively high organic C content. Further, changes accompanied by different organic carbon (C) fractions are not well understood based on long-term experiment. The knowledge of this kind is important for assessing the potential for C sequestration of a high SOC soil and selecting effective management practices for increasing soil C sequestration and productivity in agroecosystem of northeastern China. This study was aimed to assess the effects of 10 years’ organic manuring at various rates combined with chemical fertilizer on organic C sequestration in topsoil (0–20cm) and to identify changes in different SOC (total, labile, and recalcitrant) pools. Five fertilization treatments were included: (1) CK, unfertilized control; (2) OM0, only chemical fertilizer, no manure added; (3) OM1, organic manure added at 7.5Mgha−1 year−1 plus chemical fertilizer; (4) OM2, organic manure added at 15Mgha−1year−1 plus chemical fertilizer; and (5) OM3, organic manure added at 22.5Mgha−1year−1 plus chemical fertilizer. Chemical fertilizer was supplied with the same rate in each fertilized treatment. We found that the application of graded rates of manure from OM1 to OM3 significantly enhanced total SOC, labile C pools, and recalcitrant C pool as compared with OM0 and CK. The C storage (in top 20cm) in the OM0, OM1, OM2, and OM3 was increased by 3.19%, 12.5%, 14.5%, and 18.2%, respectively, over the CK treatment, suggesting that the chemical fertilizer addition had less effects on C-sequestration in topsoil compared to manure plus mineral fertilizer amendment. Moreover, topsoil C-sequestration increased with organic manure addition rates with an order of OM3 (10.5Mgha−1)>OM2 (8.4Mgha−1)>OM1 (7.2Mgha−1). A positive relationship between C sequestration and organic manure input indicates that the soil has not reached its maximum capacity of C sequestration. Application of organic manure with chemical fertilizer was found to produce greater size of both labile and recalcitrant pools than application of mineral fertilizers alone. In most cases, the increases in these C fractions were greater when organic manure was supplied at higher rates. Moreover, increase in recalcitrant C (10.5–29.5%) was significantly higher than labile C (5.6–10.2%) in manure treated plots as compared with no amendment plot. This indicated that a majority of organic C sequestered due to C inputs was accumulated and stabilized in recalcitrant C pool. In general, organic manure combined with inorganic fertilizer exerted greater influence on topsoil C storage and crop yield than chemical fertilizer alone. Based on crop yield and soil C storage, applying organic manure at the rate of 22.5Mgha−1year−1 was the most effective way to improve soil productivity and C sequestration in the agroecosystem of northeastern China. However, taking use efficiency of organic inputs and environmental factors into consideration, application of manure at moderate rate (about 15Mgha−1year−1) may be more feasible in this region.