Factors Affecting the Decomposition of Crop Residues by Microorganisms

2015 ◽  
pp. 101-129 ◽  
Author(s):  
J. F. Parr ◽  
R. I. Papendick
Keyword(s):  
Crop Residues ◽  
Factors Affecting

Factors affecting the operation of the weed-sensing Detectspray system

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Robert E. Blackshaw ◽  
Louis J. Molnar ◽  
Duane F. Chevalier ◽  
C. Wayne Lindwall
Keyword(s):  
Near Infrared ◽  
Field Experiments ◽  
Crop Residues ◽  
Soil Surface ◽  
Physical Factors ◽  
Weed Detection ◽  
Factors Affecting ◽  
Green Foxtail ◽  
Infrared Wavelengths ◽  
Herbicide Use

Field experiments were conducted for 3 yr to determine the effect of various biological and physical factors on the operation of the weed-sensing Detectspray system. Plant detection is achieved by sensors measuring differential reflectance of red and near-infrared wavelengths of light from green plants, crop residues, and soil. Weed detection was greatly reduced 70 to 80 min after sunrise and before sunset when operated at lat 50°N because of reduced solar irradiance. Tall, dense-standing crop stubble limited detection of small weeds at the soil surface. Weed detection varied with plant species. Canola with three to four leaves consistently was detected, but wheat or green foxtail usually required five to six leaves to be detected. Small weeds were detected if present at densities greater than 70 plants m−2. Growers and commercial applicators need to be aware of the limitations of the Detectspray system to use it effectively to control weeds with concurrent reductions in herbicide use.

scholarly journals Environmental Factors Affecting the Mineralization of Crop Residues

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1951
Author(s):  
Aleksandra Grzyb ◽  
Agnieszka Wolna-Maruwka ◽  
Alicja Niewiadomska
Keyword(s):  
Environmental Factors ◽  
Crop Production ◽  
Crop Residues ◽  
Management Strategies ◽  
C:N Ratio ◽  
Environment Friendly ◽  
Factors Affecting ◽  
Plant Matter ◽  
High Yields

The aim of this article is to present the issues related to the significance of microorganisms in the mineralization of crop residues and the influence of environmental factors on the rate of this process. Crop residues play a very important role in agriculture because they can be used both as an environment-friendly waste management strategy and as a means of improving soil organic matter. The inclusion of crop residues in the soil requires appropriate management strategies that support crop production and protect the quality of surface water and groundwater. Crops need nutrients for high yields; however, they can only absorb ionic forms of elements. At this point, the microorganisms that convert organically bound nitrogen, phosphorus, and sulfur into soluble NH4+, NO3−, H2PO4−, HPO42−, and SO42− ions are helpful. Mineralization is the transformation of organic compounds into inorganic ones, which is a biological process that depends on temperature, rainfall, soil properties, the chemical composition of crop residues, the structure and composition of microbial communities, and the C:N ratio in soil after the application of plant matter. An adjustment of the values of these factors enables us to determine the rate and direction of the mineralization of crop residues in soil.

LABORATORY STUDIES OF FACTORS AFFECTING MICROBIAL DEGRADATION OF WHEAT STRAW RESIDUES IN SOIL

1984 ◽  
Vol 64 (1) ◽  
pp. 9-19 ◽  
Author(s):  
M. H. PUIG-GIMENEZ ◽  
F. E. CHASE
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Crop Residues ◽  
Soil Depth ◽  
Laboratory Method ◽  
Low Fertility ◽  
Simulation Studies ◽  
Straw Decomposition ◽  
Factors Affecting ◽  
Plastic Containers

A simple laboratory method for measuring CO2 evolution from soil was developed using 580-mL plastic containers. Rate of CO2 evolution was measured by exposing 0.1 N NaOH in the closed containers for 4 h and determining the altered conductivity of the absorbent. With 400 g of soil per unit plus 0.172% straw, a coefficient of variation < 2% (total CO2 evolved, 6 wk) was typical with three replicates. Tests with two low-fertility Ontario soils showed that rate of straw decomposition was not affected significantly by fertilizer amendment or length of straw cuttings, but it did increase when soil depth was reduced; also the amount of CO2 evolved increased with duration of soil storage. The method was applied to problems relating to the Mediterranean climate, burning of crop residues, and consequent depletion of soil organic matter. Simulation studies directed towards increasing soil organic matter showed that straw decomposition rates would (1) decrease as crop residues added to soil were increased two- to fivefold, (2) recover markedly over the winter from delayed decomposition caused by the late arrival of autumn rains, and (3) be unaffected by depth of straw placement in soil. Key words: Straw decomposition, chemical fertilizer, CO2 evolution, moisture, temperature, straw placement

Environmental factors affecting the germination and seedling emergence of two populations of an emerging agricultural weed: wild lettuce (Lactuca serriola)

2019 ◽  
Vol 70 (8) ◽  
pp. 709 ◽  
Author(s):  
Aakansha Chadha ◽  
Singarayer Florentine ◽  
Bhagirath S. Chauhan ◽  
Benjamin Long ◽  
Mithila Jayasundera ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Crop Residues ◽  
Seedling Emergence ◽  
Detailed Knowledge ◽  
Burial Depth ◽  
Factors Affecting ◽  
Wild Lettuce ◽  
Lactuca Serriola ◽  
Environmental Weed ◽  
Two Populations

Wild lettuce (Lactuca serriola L.) is a significant emerging agricultural and environmental weed in many countries. This invasive species is now naturalised in Australia and is claimed to cause significant losses within the agricultural industry. Sustainable management of wild lettuce has been hampered by a lack of detailed knowledge of its seed ecology. Laboratory-based studies were performed to examine the potential influence of environmental factors including temperature and light conditions, salinity, pH, moisture availability and burial depth on the germination and emergence of two spatially distant populations of wild lettuce. Results suggested that the germination of wild lettuce seeds occurred across a broad range of temperature conditions (12-h cycle: 30°C/20°C, 25°C/15°C and 17°C/7°C) for both populations. We also found that these seeds are non-photoblastic; germination was not affected by darkness, with &gt;80% germination in darkness for both populations at all tested temperature ranges. Germination significantly declined as salinity and osmotic stress increased for both populations, with seeds from the Tempy population were more affected by NaCl &gt;100 mM than seeds from Werribee, but in neither population was there any observed effect of pH on germination (&gt;80% germination in both populations at all tested pH ranges). For both populations, germination significantly decreased as burial depth increased; however, the two populations differed with regard to response to burial depth treatment, whereby seeds from the Tempy population had higher emergence than those from Werribee at 0.5 cm burial depth. These results suggest that light-reducing management techniques such as mulching or use of crop residues will be unsuccessful for preventing germination of wild lettuce. By contrast, burial of seeds at a depth of at least 4 cm will significantly reduce their emergence.

scholarly journals Outputs: Potassium Losses from Agricultural Systems

2020 ◽  
pp. 75-97
Author(s):  
Keith Goulding ◽  
T. Scott Murrell ◽  
Robert L. Mikkelsen ◽  
Ciro Rosolem ◽  
Johnny Johnston ◽  
...  
Keyword(s):  
Crop Residues ◽  
Economic Cost ◽  
Particulate Material ◽  
Relative Importance ◽  
Agricultural Ecosystem ◽  
Runoff Water ◽  
Factors Affecting ◽  
Fine Soil ◽  
Strong Winds ◽  
Soil K Status

AbstractPotassium (K) outputs comprise removals in harvested crops and losses via a number of pathways. No specific environmental issues arise from K losses to the wider environment, and so they have received little attention. Nevertheless, K is very soluble and so can be leached to depth or to surface waters. Also, because K is bound to clays and organic materials, and adsorbed K is mostly associated with fine soil particles, it can be eroded with particulate material in runoff water and by strong winds. It can also be lost when crop residues are burned in the open. Losses represent a potential economic cost to farmers and reduce soil nutritional status for plant growth. The pathways of loss and their relative importance can be related to: (a) the general characteristics of the agricultural ecosystem (tropical or temperate regions, cropping or grazing, tillage management, interactions with other nutrients such as nitrogen); (b) the specific characteristics of the agricultural ecosystem such as soil mineralogy, texture, initial soil K status, sources of K applied (organic, inorganic), and rates and timing of fertilizer applications. This chapter provides an overview of the main factors affecting K removals in crops and losses through runoff, leaching, erosion, and open burning.

Predicting the nutritive value of tree fodder: consistency and complementarity between assessments made by Nepalese, smallholder farmers and by laboratory techniques

1997 ◽  
Vol 1997 ◽  
pp. 201-201
Author(s):  
P.J. Thorne ◽  
D.H. Walker ◽  
D.B. Subba ◽  
C.D. Wood ◽  
F.L. Sinclair ◽  
...  
Keyword(s):  
Nutritive Value ◽  
Crop Residues ◽  
Smallholder Farmers ◽  
Feeding Strategies ◽  
Value Assessment ◽  
Factors Affecting ◽  
Tree Fodder ◽  
Different Types ◽  
Effective Delivery ◽  
The Himalaya

Tree fodder is a vital dry season feed resource, used to supplement crop residues, on smallholdings in Nepal and other parts of the Himalaya. Farmers have a detailed and effective knowledge of the nutritive value of different types of tree fodder and the factors affecting this (Rusten and Gold, 1991; Thapa et al, in review). However, the implications of this knowledge for planning research to develop fodder resources and feeding strategies or for the effective delivery of research results to farmers are unclear. The study described here assessed the consistency between analytical indicators and farmers' perceptions of the nutritive value of tree fodder. The potential for using information from these two sources, in a complementary manner, to improve the focus of nutritive value assessment on farmers' needs was also examined.

Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

1977 ◽  
Vol 35 ◽  
pp. 214-217
Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly
Keyword(s):  
Image Analysis ◽  
Image Quality ◽  
Exposure Time ◽  
Image Contrast ◽  
Automated Image Analysis ◽  
Practical Application ◽  
Factors Affecting ◽  
High Image Quality ◽  
Qualitative Evidence ◽  
Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

Factors affecting microstructural scale in liquid crystalline polymers

1990 ◽  
Vol 48 (4) ◽  
pp. 220-221
Author(s):  
Christine M. Dannels ◽  
Christopher Viney
Keyword(s):  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Factors Affecting ◽  
Crystalline Polymers ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Lower Viscosity ◽  
Fine Microstructure ◽  
Planar Orientation ◽  
Strength And Stiffness

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.

Factors affecting dentist participation in a state Medicaid program

1990 ◽  
Vol 54 (11) ◽  
pp. 638-643 ◽  
Author(s):  
PC Damiano ◽  
ER Brown ◽  
JD Johnson ◽  
JP Scheetz
Keyword(s):  
Medicaid Program ◽  
Factors Affecting
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