QUALITY AND VALUE OF WIND-MOVABLE AGGREGATES IN CHERNOZEMIC Ap HORIZONS

1987 ◽  
Vol 67 (3) ◽  
pp. 601-607 ◽  
Author(s):  
J. F. DORMAAR

The 0–5 cm depth from Ap horizons of Orthic Brown, Dark Brown and Black Chernozemic soils when recently brought under cultivation, and of unfertilized Dark Brown Chernozemic soils under continuous wheat and a wheat-fallow rotation since 1912 were sampled in early May 1984. The samples were separated into 500- to 1000-μm, 250- to 500-μm, 100- to 250-μm, and < 100-μm-diameter water-stable aggregates by wet sieving. These four diameter classes of water-stable aggregates, considered to be the wind-erodible fraction of the soil, comprised 65–76% and 89–96% of the whole soil of the Ap horizons of recently and long-term cultivated soils, respectively. They were analyzed for organic matter, total N, available P, exchangeable K and monosaccharides. The source of the monosaccharides in the < 100-μm-diameter soil fraction, whether microbial or vegetative, was identified using ratios of hexoses to pentoses. The data allowed the calculation, using a number of assumptions, of the value of soil lost by wind erosion if its nutrients and organic matter had to be replaced by commercial fertilizers and cereal straw, respectively. The values obtained underscore the cost involved in poor land management, leading to wind erosion. Key words: Wind erosion, topsoil loss, organic matter (soil), monosaccharides, plant nutrients, land management

1993 ◽  
Vol 73 (4) ◽  
pp. 579-595 ◽  
Author(s):  
C. A. Campbell ◽  
D. Curtin ◽  
A. P. Moulin ◽  
L. Townley-Smith ◽  
G. P. Lafond

The impact of cultural practices on soil aggregate characteristics which determine the susceptibility of the soil to wind and water erosion was studied at two long-term (> 30-yr) crop rotation sites on Black Chernozemic soils at Indian Head and Melfort, Saskatchewan. Surface soil (top 5 cm) taken in spring and fall, 1991, was air-dried and sieved by rotary sieve to measure aggregate size distribution. The water-stability of soil aggregates (1–2 mm) was determined after: (i) slow wetting, and (ii) fast wetting. Both rotation studies employed conventional tillage management until 1990 when the Indian Head experiment was converted to zero-tillage. Summerfallowing increased the wind-erodible (< 0.84-mm) fraction of soil and decreased the geometric mean diameter (GMD) of aggregates. One year of cropping was sufficient to significantly reduce the proportion of wind-erodibile aggregates. Fertilization and legume green manure and hay crops reduced the wind-erodible fraction at Indian Head, but had no effect on the higher organic matter soil at Melfort. In monoculture wheat systems at Indian Head there was an inverse relationship between the wind-erodible fraction and cropping frequency; this was credited to the positive influence of cropping frequency on crop residue production. The wind-erodible fraction (Y) was related to GMD at Indian Head: Y = 11.8 + 117/GMD (r2 = 0.80***), and at Melfort, Y = 11.9 + 91/GMD (r2 = 0.82***). When subjected to rapid wetting, both the difference between cropped and native grassland soils, and the influence of cultural practices on water stable aggregates were pronounced. Aggregate stability was more closely related to the long-term management than to recent (< 1 yr) cultural treatments. Frequent cropping, fertilization, and use of legumes increased water stable aggregates, particularly at the Indian Head site with its lower organic matter content. Key words: Wet sieving, dry sieving, legumes, fertilization, geometric mean diameter, wind erosion


1999 ◽  
Vol 79 (3) ◽  
pp. 419-425 ◽  
Author(s):  
M. Aoyama ◽  
D. A. Angers ◽  
A. N'Dayegamiye ◽  
N. Bissonnette

Effects of long-term (18-yr) applications of cattle manure (20 Mg ha−1 yr−1) and NPK fertilizer on the labile organic matter (OM) and its protection in water-stable aggregates were investigated in a Le Bras silt loam (Humic Gleysol). Soil from the 0- to 10-cm depth was sampled from the untreated control, NPK, manure and NPK + manure treatments and fractionated into four size classes of slaking-resistant aggregates (>1000 µm, 250–1000 µm, 53–250 µm, <53 µm). Intact and crushed macroaggregates (250–1000 and >1000 µm) and intact microaggregates (<250 µm) were incubated for 21 d at 25 °C, and mineralized C and N were determined. The amount of mineralized C in intact aggregates increased with increasing aggregate size irrespective of the agronomic treatments, but there was no consistent trend for total N. Manure application led to an increase in mineralized C in most aggregate fractions. Crushing the macroaggregates enhanced mineralization of C by 14 to 35% and N by 17 to 103%. Additional C and N rendered mineralizable by crushing represents a fraction of the macroaggregate-protected OM. Manure application increased the protected pools of C (up to threefold) and N (up to fourfold) located in the small macroaggregates (250–1000 µm). In contrast, NPK fertilization increased the pool of macroaggregate-protected N by 2.5-fold but had no effect on the protected C. We conclude that manure application contributed to the accumulation of macroaggregate-protected C and N, whereas mineral fertilizers increased the protected-N pool only. Macroaggregates can provide a mechanism for the protection of labile soil OM in an annually tilled cropping system and this mechanism is enhanced with long-term manure application. Key words: Aggregate-protected organic matter, manure application, mineralization, mineral fertilizer, water-stable aggregates


2018 ◽  
Vol 13 (No. 3) ◽  
pp. 140-149 ◽  
Author(s):  
Šimanský Vladimír ◽  
Lukáč Martin

Soil structure is a key determinant of many soil environmental processes and is essential for supporting terrestrial ecosystem productivity. Management of arable soils plays a significant role in forming and maintaining their structure. Between 1994 and 2011, we studied the influence of soil tillage and fertilisation regimes on the stability of soil structure of loamy Haplic Luvisol in a replicated long-term field experiment in the Dolná Malanta locality (Slovakia). Soil samples were repeatedly collected from plots exposed to the following treatments: conventional tillage (CT) and minimum tillage (MT) combined with conventional (NPK) and crop residue-enhanced fertilisation (CR+NPK). MT resulted in an increase of critical soil organic matter content (St) by 7% in comparison with CT. Addition of crop residues and NPK fertilisers significantly increased St values (by 7%) in comparison with NPK-only treatments. Soil tillage and fertilisation did not have any significant impact on other parameters of soil structure such as dry sieving mean weight diameters (MWD), mean weight diameter of water-stable aggregates (MWD<sub>WSA</sub>), vulnerability coefficient (Kv), stability index of water-stable aggregates (Sw), index of crusting (Ic), contents of water-stable macro- (WSA<sub>ma</sub>) and micro-aggregates (WSA<sub>mi</sub>). Ic was correlated with organic matter content in all combinations of treatments. Surprisingly, humus quality did not interact with soil management practices to affect soil structure parameters. Higher sums of base cations, CEC and base saturation (Bs) were linked to higher Sw values, however higher values of hydrolytic acidity (Ha) resulted in lower aggregate stability in CT treatments. Higher content of K<sup>+</sup> was responsible for higher values of MWD<sub>WSA </sub>and MWD in CT. In MT, contents of Ca<sup>2+</sup>, Mg<sup>2+ </sup>and Na<sup>+</sup> were significantly correlated with contents of WSA<sub>mi </sub>and WSA<sub>ma</sub>. Higher contents of Na<sup>+</sup> negatively affected St values and positive correlations were detected between Ca<sup>2+</sup>, Mg<sup>2+ </sup>and Na<sup>+</sup> and Ic in NPK treatments.


2016 ◽  
Vol 22 ◽  
pp. 23-36 ◽  
Author(s):  
Nicholas P. Webb ◽  
Jeffrey E. Herrick ◽  
Justin W. Van Zee ◽  
Ericha M. Courtright ◽  
Christopher H. Hugenholtz ◽  
...  

Soil Research ◽  
1993 ◽  
Vol 31 (4) ◽  
pp. 481 ◽  
Author(s):  
MR Carter ◽  
WJ Parton ◽  
IC Rowland ◽  
JE Schultz ◽  
GR Steed

Maintenance and improvement of soil organic matter levels is an important concern in dryland farming systems of temperate regions. The Century soil organic matter model was used to simulate changes in soil organic C and total N under long-term wheat (Triticum aestivum L.) and pasture rotations at five sites in southern Australia. Average declines in soil organic C and total N of 14 and 10%, respectively, in continuous and wheat-fallow systems over a 10 to 20 year period were closely simulated by the model at each site. Additions of N fertilizer (80 kg N ha-1), which prevented soil organic matter decline in continuous wheat systems, was also well represented by the model. Trends in soil organic matter under long-term legume pasture were not adequately simulated by the model, probably due to the 'annual' nature of subterranean clover (Trifolium subterranean L.) in dry seasons and subsequent changes in the ratio of live to dead plant biomass and shoot to root ratios. Overall, the study emphasizes the importance of adequate total plant C production to prevent a decline in soil organic C.


2021 ◽  
Author(s):  
Carlos Romero ◽  
Xiying Hao ◽  
Paul Hazendonk ◽  
Timothy Schwinghamer ◽  
Martin Chantigny ◽  
...  

&lt;p&gt;Managing croplands for increased storage of soil organic matter (SOM) is a critical step towards developing resilient farming systems in a changing climate. We examined SOM dynamics in a wheat (Triticum durum L.) &amp;#8211; maize (Zea mays L.) irrigated bed planting system established near Ciudad Obreg&amp;#243;n, Sonora, Mexico. Soil samples (0 &amp;#8211; 15 cm) were collected from conventionally tilled raised beds (CTB) with all crop residues incorporated (CTB-I) and permanent raised beds (PB) with crop residues burned (PB-B), removed (PB-R), partly retained (PB-P) or fully retained (PB-K) receiving 0, 150 or 300 kg N ha&lt;sup&gt;-1&lt;/sup&gt;, and analyzed for organic C (OC), total N (TN) and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C in whole-soil, light fraction (LF) and coarse- (sand) and fine- (silt and clay) mineral-associated organic matter (MAOM). Results indicated that PB-K and PB-B increased soil OC (P &lt; 0.05) in whole-soil relative to CTB-I, mainly through increases in sand- and silt-size MAOM, respectively. Similarly, N-fertilization increased soil OC and TN contents in whole-soil, coarse-MAOM, and fine-MAOM, but not in the LF pool. Soil &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C was higher (P &lt; 0.05) in PB-K (-20.18&amp;#8240;) relative to PB-B (-20.67&amp;#8240;), possibly due to the stabilization of partly decomposed maize-C in silt- and clay-size MAOM. The composition of SOM surveyed by CPMAS &lt;sup&gt;13&lt;/sup&gt;C NMR was not affected by tillage-residue management and roughly consisted of 35% O-alkyl-C, 31% alkyl-C, 24% aromatic-C, and 10% carboxyl-C. Our results indicate that long-term PB-K and PB-B adoption increased surface soil OC contents relative to CTB-I, even though pathways of SOM stabilization differed between systems. Under PB-K, accumulation of fine-MAOM was mostly related to straw-C inputs, whereas in PB-B it was closely associated with black-C precursors. Fine-MAOM appeared responsive to crop residue management and should be therefore considered when analyzing mechanisms of SOM stabilization in irrigated croplands.&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.5f4bda4b7cff54512830161/sdaolpUECMynit/12UGE&amp;app=m&amp;a=0&amp;c=e41c23ac3d107ae401152ab2ecf4553d&amp;ct=x&amp;pn=gepj.elif&amp;d=1&quot; alt=&quot;&quot;&gt;&lt;/p&gt;


2020 ◽  
Vol 12 (21) ◽  
pp. 9008
Author(s):  
Shadman Khan ◽  
Zahir Shah ◽  
Ishaq Ahmad Mian ◽  
Khadim Dawar ◽  
Muhammad Tariq ◽  
...  

A research study was established at the research farm of the University of Agriculture, Peshawar during winter 2018–2019. Commercial biochars were given to the experimental site from 2014 to summer 2018 and received 0.95, 130 and 60 tons ha−1 of biochar by various treatments viz., (Biochar1) BC1, (Biochar2) BC2, (Biochar3) BC3 and (Biochar4) BC4, respectively. This piece of work was conducted within the same study to find the long-term influence of biochar on the fertility of the soil, fixation of N2, as well as the yie1d of chickpea under a mung–chickpea cropping system. A split plot arrangement was carried out by RCBD (Randomized Complete Block Design) to evaluate the study. Twenty-five kilograms of N ha−1 were given as a starter dosage to every plot. Phosphorous and potassium were applied at two levels (half (45:30 kg ha−1) and full (90:60 kg ha−1) recommended doses) to each of the four biochar treatments. The chickpea crop parameters measured were the numbers and masses of the nodules, N2 fixation and grain yield. Soil parameters recorded were Soil Organic Matter (SOM), total N and mineral N. The aforementioned soil parameters were recorded after harvesting. The results showed that nodulation in chickpea, grain yield and nutrient uptake were significantly enhanced by phosphorous and potassium mineral fertilizers. The application of biochar 95 tons ha−1 significantly enhanced number of nodules i-e (122), however statistically similar response in terms of nodules number was also noted with treatment of 130 tons ha−1. The results further revealed a significant difference in terms of organic matter (OM) (%) between the half and full mineral fertilizer treatments. With the application of 130 tons ha−1 of biochar, the OM enhanced from 1.67% in the control treatment, to 2.59%. However, total and mineral nitrogen were not statistically enhanced by the mineral fertilizer treatment. With regard to biochar treatments, total and mineral N enhanced when compared with the control treatment. The highest total N of 0.082% and mineral nitrogen of 73 mg kg−1 in the soil were recorded at 130 tons ha−1 of biochar, while the lowest total N (0.049%) and mineral nitrogen (54 mg kg−1) in the soil were recorded in the control treatment. The collaborative influence of mineral fertilizers and biochars was found to be generally non-significant for most of the soil and plant parameters. It could be concluded that the aforementioned parameters were greater for treatments receiving biochar at 95 tons or more per hectare over the last several years, and that the combination of lower doses of mineral fertilizers further improved the performance of biochar.


1979 ◽  
Vol 59 (2) ◽  
pp. 79-86 ◽  
Author(s):  
J. F. DORMAAR ◽  
U. J. PITTMAN ◽  
E. D. SPRATT

Soils from a long-term spring wheat — spring wheat — fallow crop rotation study at Lethbridge, Alberta, and two similar crop rotations at Indian Head, Saskatchewan, were analyzed for pH, organic C, total N, chelating resin-extractable C, polysaccharides, water-stable aggregates, NH4-N, NO3-N, and available P. Several agronomic practices, including straw burning, have been tested in the rotations. At Lethbridge, soil samples from the straw-burning treatment showed a decrease (P < 0.05) in soil polysaccharides and in the percentage of water-stable aggregates. At Indian Head, where straw was burned, organic C and polysaccharide content of all soils were decreased (P < 0.05), and NH4-N and available P were decreased (P < 0.05) in some soils. The other soil characteristics examined were not affected by burning of the previous crop residue or, as with available P, reacted differently at different sites. Long-term wheat yields tended to be greater in all experiments when straw was not burned. On the basis of the results obtained, burning of crop residues on a long-term basis must be discouraged.


Author(s):  
Mervin St. Luce ◽  
Noura Ziadi ◽  
Martin H. Chantigny ◽  
Justin Braun

Tillage and nitrogen (N) fertilization can influence soil organic matter (SOM) dynamics, but their interactive effects remain contradictory. A long-term (25 yr) corn (Zea mays L.)-soybean (Glycine max L. Merr.) rotation was used to investigate the effect of tillage [moldboard plow (MP) and no-till (NT)] and N rates (0, 80 and 160 kg N ha-1) on soil organic carbon (SOC), total N (STN), respiration, and SOM fractions [particulate organic matter (POMC, POMN), mineral-associated organic matter (MAOMC, MAOMN), and microbial biomass (MBC, MBN)]. Results indicate that NT had 27% higher SOC and 24% higher STN than MP in the 0-20 cm depth. Furthermore, SOC and STN stocks (0-20 cm) were 22% and 20% higher, respectively, under NT than MP. There was significant stratification under NT, with a rather uniform distribution under MP. The SOM fractions and soil respiration were 28-275% and 20-83% higher at the 0-5 and 5-10 cm depths, respectively, under NT than MP. Interestingly, N fertilizer rate or its interaction with tillage had no impact, except for respiration (tillage × N rate and N rate × depth). Hence, while N addition was required for adequate grain production and increased cumulative plant C and N inputs, our findings indicate that the vertical distribution of SOC, STN and SOM fractions were affected by tillage, thereby influencing resource accessibility and subsequent dynamics of SOM fractions. Taken together, our results support the adoption of NT and judicious use of N fertilizers for enhancing topsoil SOM storage and fertility under humid temperate conditions.


Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1977
Author(s):  
Ayumi Koishi ◽  
Luca Bragazza ◽  
Alexandra Maltas ◽  
Thomas Guillaume ◽  
Sokrat Sinaj

Increasing soil organic carbon (SOC) in agroecosystems is a promising solution to simultaneously address climate change mitigation, adaptation, and food security. Yet, the best management practices that could achieve these goals remain to be identified. Here, we analyze the long-term effects of application of green manure, cereal straw, farmyard manure, and cattle slurry on SOC in a 37 year long field experiment in Switzerland. The treatment effects were compared against control conditions that received only optimal mineral fertilization. More specifically, this study aimed at evaluating the effect of organic amendments on SOC accumulation and distribution in different soil particle-size fractions by means of a set of indicators about organic matter quality (biological reactivity, humification index) and microbial activity (extracellular enzyme activities). In the absence of organic matter input, application of mineral fertilizers alone resulted in the lowest SOC content and the highest humification index of the bulk soil organic matter. Among the organic amendments, cereal straw, farmyard manure, and cattle slurry promoted a higher SOC content and a lower humification index due to an increase of SOC in the clay-size fraction. The annual C accrual reached 4.4‰ per year over 37 years with farmyard manure. The higher biological reactivity measured for the green manure and cereal straw amendments was associated with higher soil enzymatic activities, while C retention coefficients decreased by at least 2.5 times compared to animal-derived amendments. The low availability of nutrients in green manure and straw amendments as suggested by the high phosphatase and N-acetylglucosaminidase activities may indicate a reduction in C retention of organic matter inputs due to nutrient microbial mining with plant-derived amendments.


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