The influence of different cover crop residues quantities on soil structural stability

Author(s):  
Gheorghe Stegarescu ◽  
Endla Reintam ◽  
Tõnu Tõnutare

<p>Cover crops are widely known for their capacity to improve the soil biological properties and soil structural stability. Nevertheless, the cover crop residues quantity necessary to improve these soil properties is not yet really known. A 30-day incubation experiment was conducted to explore the effect of oilseed rape (Brassica napus) residues (ORR) as a cover crop on the soil aggregate stability of sandy loam soil. The fresh ORR was mixed with the soil at different rates starting from 1.0 to 6.0 g C kg<sup>-1</sup> of soil. The experiment consisted of five treatments: bulk soil (I), soil mixed with ORR at a rate of 1 g C kg<sup>-1</sup> of soil (II), soil mixed with ORR at a rate of 2 g C kg<sup>-1</sup> of soil (III), soil mixed with ORR at a rate of 4 g C kg<sup>-1</sup> of soil (IV), soil mixed with ORR at a rate of 6 g C kg<sup>-1</sup> of soil (V). During 30 days of incubation the soil moisture, soil water stable aggregates, and microbial substrate induced respiration rates were measured. The aggregate stability significantly increased after 30 days only in the treatment with 1 g C kg<sup>-1</sup> of soil. In turn, the ORR applied at a rate of 6 g C kg<sup>-1</sup> of soil significantly decreased the soil aggregate stability. The higher the ORR addition rate the lower was the soil basal respiration and substrate induced respiration. The general conclusion was that the higher quantity of ORR increased the soil moisture which subsequently created unfavorable conditions for the soil microbial activity and led to soil aggregate stability degradation. However, this conclusion must be validated in a field study where the soil moisture and temperature conditions are much more variable compared to our incubation experiment.</p>

Soil Research ◽  
2014 ◽  
Vol 52 (4) ◽  
pp. 317 ◽  
Author(s):  
A. I. Mamedov ◽  
B. Bar-Yosef ◽  
I. Levkovich ◽  
R. Rosenberg ◽  
A. Silber ◽  
...  

Recycling of organic wastes via their incorporation in cultivated lands is known to alter soil structural stability. Aggregate stability tests are commonly used to express quantitatively the susceptibility of soil structural stability to deformation. The objective of this study was to investigate the effects of biosolids addition, namely composted manure (MC) and activated sludge (AS), and spiking of the soils with orthophosphate (OP), phytic acid (PA) or humic acid (HA), on soil aggregate stability of semi-arid loamy sand, loam and clay soils before and after subjecting the soils to six rain storms (each 30 mm rain with a break of 3–4 days). Aggregate stability was determined from water-retention curves at high matric potential. The effects of the applied amendments on pre- and post-rain aggregate stability were inconsistent and soil-dependent. For the pre-rain state, all of the tested amendments improved aggregate stability relative to the control. For the post-rain condition, aggregate stability was lower in the MC, OP and PA treatments and higher in the AS and HA treatments than in the control. The coarse-textured loam and loamy sand soils were more affected by the soil amendments than the clay soil. For the pre-rain state, addition of organic matter significantly improved macro-porosity and hence the stability of apparent macro-aggregate (>250 μm). Our results indicate a possible advantage for separation of aggregates into macro- and micro-aggregates for more precise evaluation and understanding of the effects organic amendments might have on aggregate stability.


2020 ◽  
Vol 100 (3) ◽  
pp. 314-318
Author(s):  
April Stainsby ◽  
William E. May ◽  
Guy P. Lafond ◽  
Martin H. Entz

Black medic (Medicago lupulina L.) is a self-regenerating cover crop which was tested for its ability to improve soil physical properties. Soil aggregate stability was assessed in plots that included a black medic cover crop in a no-till grain rotation, which was fertilized with two levels of nitrogen (N), for 15 yr. In the wheat phase of the rotation, the medic cover crop increased mean weight diameter by 21% in the reduced N fertilizer treatment but not in the recommended N treatment. Generally, the addition of medic reduced the proportion of small aggregates and increased the proportion of large aggregates. This pattern was stronger in reduced N compared with recommended N fertilizer levels. This study provided evidence for medic to increase aggregate stability under low external N input grain production.


Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 527
Author(s):  
Gheorghe Stegarescu ◽  
Jordi Escuer-Gatius ◽  
Kaido Soosaar ◽  
Karin Kauer ◽  
Tõnu Tõnutare ◽  
...  

The decomposition of fresh crop residues added to soil for agricultural purposes is complex. This is due to different factors that influence the decomposition process. In field conditions, the incorporation of crop residues into soil does not always have a positive effect on aggregate stability. The aim of this study was to investigate the decomposition effects of residues from two different cover crops (Brassica napus var. oleifera and Secale cereale) and one main crop (wheat straw) on soil aggregate stability. A 105-day incubation experiment was conducted in which crop residues were mixed with sandy loam soil at a rate of 6 g C kg−1 of soil. During the incubation, there were five water additions. The decomposition effects of organic matter on soil conditions during incubation were evaluated by determining the soil functional groups; carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) emissions; soil microbial biomass carbon (MBC); and water-stable aggregates (WSA). The functional groups of the plant residues and the soil were analyzed using Fourier transform infrared spectroscopy (FTIR) and a double exponential model was used to estimate the decomposition rates. The results show that the decomposition rate of fresh organic materials was correlated with the soil functional groups and the C/N ratio. Oilseed rape and rye, with lower C/N ratios than wheat straw residues, had faster decomposition rates and higher CO2 and N2O emissions than wheat straw. The CO2 and N2O flush at the start of the experiment corresponded to a decrease of soil aggregate stability (from Day 3 to Day 10 for CO2 and from Day 19 to Day 28 for N2O emissions), which was linked to higher decomposition rates of the labile fraction. The lower decomposition rates contributed to higher remaining C (carbon) and higher soil aggregate stability. The results also show that changes in the soil functional groups due to crop residue incorporation did not significantly influence aggregate stability. Soil moisture (SM) negatively influenced the aggregate stability and greenhouse gas emissions (GHG) in all treatments (oilseed rape, rye, wheat straw, and control). Irrespective of the water addition procedure, rye and wheat straw residues had a positive effect on water-stable aggregates more frequently than oilseed rape during the incubation period. The results presented here may contribute to a better understanding of decomposition processes after the incorporation of fresh crop residues from cover crops. A future field study investigating the influence of incorporation rates of different crop residues on soil aggregate stability would be of great interest.


2008 ◽  
pp. 23-32
Author(s):  
Andrea Huisz ◽  
Tibor Tóth ◽  
Tamás Németh

Soil structure may be improved by adding readily decomposable organic matter. The extent of amelioration depends on the chemical build-up and decomposability of the crop residues. Three different kinds of organic matters were investigated: (1) maize stem, (2) wheat straw, and (3) maize stem& wheat straw. Comparing the aggregate stabilizing effects of the differently decomposable organic matters to each other, the expected maize stem & wheat straw (mw) > maize stem (m) > wheat straw (w) order was proved.


Author(s):  
Surachet Aramrak ◽  
Natthapol Chittamart ◽  
Worachart Wisawapipat ◽  
Wutthida Rattanapichai ◽  
Mutchima Phun-Iam ◽  
...  

2021 ◽  
Vol 13 (3) ◽  
pp. 1541
Author(s):  
Xiaolin Shen ◽  
Lili Wang ◽  
Qichen Yang ◽  
Weiming Xiu ◽  
Gang Li ◽  
...  

Our study aimed to provide a scientific basis for an appropriate tillage management of wheat-maize rotation system, which is beneficial to the sustainable development of agriculture in the fluvo-aquic soil areas in China. Four tillage treatments were investigated after maize harvest, including rotary tillage with straw returning (RT), deep ploughing with straw returning (DP), subsoiling with straw returning (SS), and no tillage with straw mulching (NT). We evaluated soil organic carbon (SOC), dissolved organic carbon (DOC), permanganate oxidizable carbon (POXC), microbial biomass carbon (MBC), and particulate organic carbon (POC) in bulk soil and soil aggregates with five particle sizes (>5 mm, 5–2 mm, 2–1 mm, 1–0.25 mm, and <0.25 mm) under different tillage managements. Results showed that compared with RT treatment, NT treatment not only increased soil aggregate stability, but also enhanced SOC, DOC, and POC contents, especially those in large size macroaggregates. DP treatment also showed positive effects on soil aggregate stability and labile carbon fractions (DOC and POXC). Consequently, we suggest that no tillage or deep ploughing, rather than rotary tillage, could be better tillage management considering carbon storage. Meanwhile, we implied that mass fractal dimension (Dm) and POXC could be effective indicators of soil quality, as affected by tillage managements.


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