Soil Fertility, Mineral Nitrogen, and Microbial Biomass in Upland Soils of the Central Amazon under Different Plant Covers

A study was carried out to compare the fertility of soils under improved soil management practice with that of prevailing conventional practice and to assess the farmers’ perception on the improved practice in the upland farming system. The study was carried out in Nasikasthan Sanga of Kavrepalanchok district of Nepal. Soil samples were collected from fields under improved conventional practice. Samples were taken at 0-15 and 15-30 cm depths and were analyzed for various physico-chemical properties to compare the fertility status of the soils under both the practices. Altogether 68 farmers were interviewed to have information on farming practices and information pertinent to improved soil management practice being adopted by them. Results from soil physico-chemical analysis showed higher fertility of soils under improved practice in terms of more favorable pH level, contents of exchangeable bases, available phosphorus and soil organic matter compared to prevailing conventional soil management practice. Moreover, majority of the farmers believed that soil fertility and physical condition of their upland soils had improved and that the productivity of major upland crops had also increased after the adoption of improved soil management practice. Improved practice could play an important role in the sustainable management of upland soils in the mid hills of Nepal. It is however, desirable to conduct long-term research to further ascertain the effect of the practice on soil fertility of different soil types and land uses.Nepal Agric. Res. J. Vol. 9, 2009, pp. 27-39DOI: http://dx.doi.org/10.3126/narj.v9i0.11639

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Effects of lupin-wheat rotations on soil fertility, crop disease and crop yields

Australian Journal of Experimental Agriculture ◽

10.1071/ea9840595 ◽

1984 ◽

Vol 24 (127) ◽

pp. 595 ◽

Cited By ~ 46

Author(s):

TG Reeves ◽

A Ellington ◽

HD Brooke

Keyword(s):

Soil Fertility ◽

Crop Yields ◽

Disease Incidence ◽

Mineral Nitrogen ◽

Gaeumannomyces Graminis ◽

Wheat Crop ◽

Soil Mineral ◽

Soil Mineral Nitrogen ◽

Nitrogen Levels ◽

Crop Diseases

Three experiments, begun in successive years, were conducted between 1974 and 1979 in north-eastern Victoria to investigate the effects of rotating wheat (cv. Olympic) and 'sweet' lupins (Lupinus angustifolius cv. Uniharvest) on crop yields, soil fertility and crop diseases. The grain yield of continuous wheat was 2.58 t/ha and of continuous lupins 0.66 t/ha (P<0.05). Wheat, grown after a lupin crop, yielded 750 kg/ha more than wheat after wheat, and a second wheat crop, after lupins, yielded 420 kg/ha more than a third successive wheat crop. Lupins, grown after wheat, yielded 50-165% more than lupins after lupins. Grain nitrogen of wheat was significantly increased after lupins (P<0.01). Differences in soil mineral nitrogen were apparent ten weeks after sowing, with mean nitrogen levels of 37 and 55 kg/ha under wheat and lupins, respectively. Soil mineral nitrogen (0-20 cm) was consistently greater after lupins than after wheat (P<0.01) when measured just before seeding the succeeding crop. Overall, mean accretion of mineral nitrogen under lupins was 4 1 kg/ha.year. Residual nitrogen from lupins, after one succeeding wheat crop had been grown, was also evident (mean 23 kg/ha). Crop rotation influenced the incidence of crop diseases in wheat and lupins. Lupins after lupins suffered severely from brown leaf spot (Pleiochaeta setosa), up to 63% of plants being infected compared with only 18% after wheat. Disease incidence (mainly Gaeumannomyces graminis) in wheat increased from less than 1% in the first year of cropping, to 36% infection in year 3. When wheat was grown after lupins, disease incidence was negligible.

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Corrigenda - Temporal fluctuations in biochemical properties of soil under pasture. I. Respiratory activity and microbial biomass

Soil Research ◽

10.1071/sr9840303c ◽

1984 ◽

Vol 22 (3) ◽

pp. 303

Author(s):

DJ Ross ◽

VA Orchard ◽

DA Rhoades

Keyword(s):

Soil Moisture ◽

Microbial Biomass ◽

Moisture Content ◽

Respiratory Activity ◽

Mineral Nitrogen ◽

Co2 Production ◽

Biomass Carbon ◽

Moist Soil ◽

Glucose Response ◽

Temporal Fluctuations

Temporal fluctuations in respiratory activity (CO2 production) and two indices of microbial biomass (biomass carbon and mineral-nitrogen flush contents) were determined in topsoil, predominantly a Typic Haplaquoll, from a site under grazed pastures in the Wairarapa area. Samples, with organic carbon contents averaging 6.7 and 3.6%, were taken from two separate plots at c. 4-weekly intervals for over a year. Biomass indices were estimated by the chloroform fumigation technique. The suitability of a physiological procedure for indicating biomass fluctuations was also investigated. Correlations between properties were calculated with plot effects removed. Rates of CO2 production by field-moist soil, and soil at a standardized water potential, were lowest in samples taken at the driest time of the year and correlated significantly with field-moisture content. In contrast, biomass carbon estimates were generally highest in late summer and autumn, and lowest in winter, and were correlated negatively with soil moisture content. Mineral-nitrogen flush fluctuations were less marked, and not significantly related to soil moisture or biomass carbon content. In the physiological procedure, using field-moist soil, neither rates of CO2 production by soil + glucose, nor net glucose response values, were correlated significantly with biomass carbon estimated by the fumigation technique. This procedure therefore appears unsuitable for estimating temporal fluctuations in the biomass of an individual soil under pasture.

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The Azotobacter Test of Soil Fertility Applied to the Classical Fields at Rothamsted.

The Journal of Agricultural Science ◽

10.1017/s0021859600054605 ◽

1932 ◽

Vol 22 (4) ◽

pp. 797-810 ◽

Cited By ~ 11

Author(s):

Jadwiga Ziemięcka

Keyword(s):

Calcium Carbonate ◽

Soil Fertility ◽

Soil Samples ◽

Mineral Nitrogen ◽

Nitrogen Compounds ◽

Phosphate Content ◽

Plate Test ◽

Classical Fields ◽

Available Phosphate

Summary and abstract1. The kneaded plate (plaque moulée) method of detecting deficiency in lime and available phosphate was applied to seventy-nine soil samples taken from the classical Rothamsted arable plots, and the Azotobacter population from some of these samples was estimated by counts on silica jelly.2. The silica jelly counts showed that Azotobacter cells were very much reduced in number, or even absent in soil receiving 86 lb. per acre or more of mineral nitrogen. It is suggested that this is due to competition with other organisms whose growth is stimulated by added nitrogen compounds.3. The kneaded-plate test correctly indicaṫed whether phosphate had been applied in soils receiving little or no nitrogen manures.4. In those soils receiving 86 lb. or more of mineral nitrogen, the kneaded-plate test usually showed little or no Azotobacter growth even in the presence of phosphate and calcium carbonate. This failure was probably due to the paucity of Azotobacter cells originally present in such soil samples. In some cases the test was modified by inoculating the sample with a culture of Azotobacter and it then gave correct indications as to phosphate content.

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Effect of distance and depth on microbial biomass and mineral nitrogen content under Acacia senegal (L.) Willd. trees

Journal of Environmental Management ◽

10.1016/j.jenvman.2011.03.038 ◽

2012 ◽

Vol 95 ◽

pp. S260-S264 ◽

Cited By ~ 13

Author(s):

Dioumacor Fall ◽

Diegane Diouf ◽

Alzouma Mayaki Zoubeirou ◽

Niokhor Bakhoum ◽

Aliou Faye ◽

...

Keyword(s):

Microbial Biomass ◽

Nitrogen Content ◽

Mineral Nitrogen ◽

Acacia Senegal

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Management of sugarcane harvest residues: consequences for soil carbon and nitrogen

Soil Research ◽

10.1071/sr06080 ◽

2007 ◽

Vol 45 (1) ◽

pp. 13 ◽

Cited By ~ 83

Author(s):

Fiona A. Robertson ◽

Peter J. Thorburn

Keyword(s):

Microbial Biomass ◽

Soil Fertility ◽

Microbial Activity ◽

Soil N ◽

Soil Organic C ◽

Total N ◽

Organic C ◽

Soil Microbial ◽

C And N

The Australian sugar industry is moving away from the practice of burning the crop before harvest to a system of green cane trash blanketing (GCTB). Since the residues that would have been lost in the fire are returned to the soil, nutrients and organic matter may be accumulating under trash blanketing. There is a need to know if this is the case, to better manage fertiliser inputs and maintain soil fertility. The objective of this work was to determine whether conversion from a burning to a GCTB trash management system is likely to affect soil fertility in terms of C and N. Indicators of short- and long-term soil C and N cycling were measured in 5 field experiments in contrasting climatic conditions. The effects of GCTB varied among experiments. Experiments that had been running for 1–2 years (Harwood) showed no significant trash management effects. In experiments that had been running for 3–6 years (Mackay and Tully), soil organic C and total N were up to 21% greater under trash blanketing than under burning, to 0.10 or 0.25 m depth (most of this effect being in the top 50 mm). Soil microbial activity (CO2 production) and soil microbial biomass also increased under GCTB, presumably as a consequence of the improved C availability. Most of the trash C was respired by the microbial biomass and lost from the system as CO2. The stimulation of microbial activity in these relatively short-term GCTB systems was not accompanied by increased net mineralisation of soil N, probably because of the greatly increased net immobilisation of N. It was calculated that, with standard fertiliser applications, the entire trash blanket could be decomposed without compromising the supply of N to the crop. Calculations of possible long-term effects of converting from a burnt to a GCTB production system suggested that, at the sites studied, soil organic C could increase by 8–15%, total soil N could increase by 9–24%, and inorganic soil N could increase by 37 kg/ha.year, and that it would take 20–30 years for the soils to approach this new equilibrium. The results suggest that fertiliser N application should not be reduced in the first 6 years after adoption of GCTB, but small reductions may be possible in the longer term (>15 years).

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