Soil organic and organomineral fractions as indicators of the effects of land management in conventional and organic sugar cane systems

Soil Research ◽  
2017 ◽  
Vol 55 (2) ◽  
pp. 145 ◽  
Author(s):  
Carolina B. Brandani ◽  
Thalita F. Abbruzzini ◽  
Richard T. Conant ◽  
Carlos Eduardo P. Cerri

Brazilian sugar cane production has undergone changes in residue management. To better understand the dynamics of soil C and N in soil organic matter (SOM) fractions resulting from sugar cane management practices, we determined: the effects of different sugar cane management on the C and N content of SOM fractions; the effects of crop management, soil texture, depth and different organic matter additions on changes in 13C/12C and 15N/14N isotope composition; and the amount of SOC derived from different sources. Physical fractionation of SOM was performed for soils cultivated under four sugar cane managements, namely straw burning(SB), green cane (GC) and organic systems consisting of sugar cane grown under GC harvesting with high inputs of organic residues for 4 and 12 years (O-4 and O-12 respectively), as well as from a native vegetation (NV) area (Goianésia, Brazil). Ultrasonic dispersion of soil samples from 0–5, 5–10, 10–20 and 90–100-cm depths resulted in three organomineral fractions (<53, 75–53 and 2000–75µm) and one organic fraction denoted as light fraction (2000–75µm). C and N concentrations, 13C and 15N natural abundance and the proportion of C derived from C4 sugar cane plant residues (C-C4) were determined for each fraction. The C management index (CMI), derived from the total C pool and C lability, is useful in evaluating the capacity of management systems to improve soil quality and was calculated using the NV as the reference. Highest C and N concentrations were found for O-12 and O-4, mainly for the <53-µm organomineral fraction at 0–5cm depth. The 13C and C-C4 values indicated a greater accumulation of C-C4 in SOM fractions in organic compared with burned and unburned systems. GC combined with organic management is a strategy for long-term storage of total C and N in the SOM fraction associated with <53-µm fraction and light fraction. In addition, the highest CMI and its positive relationship with C-C4 in O-12 suggest the role of this system to foster soil quality improvement. The results allow infer regarding the potential of management practices on C accumulation in SOM fractions, which, in turn, can be used as indicators of the effects of land management.

Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 35 ◽  
Author(s):  
Telak ◽  
Bogunovic ◽  
Rodrigo-Comino

Humans are the driving factor of soil erosion and degradation. Therefore, sustainable land management practices should be developed and applied. The aim of this study was to determine land management impacts on soil properties, soil loss and nutrient loss in 3 different treatments; grass-covered vineyard (GCV), tilled vineyard (TV), and tilled hazelnut orchard (HO). The study area is located in Orahovica, Croatia (45°31′ N, 17°51′ E; elevation 230 m) on ~7° slope. The soil under the study area was classified as a Stagnosol. 8 rainfall simulations (58 mm h−1, during 30 min, over 0.785 m2 plots) were performed at each treatment where the next data were noted: ponding time, runoff time, and collection of overland flow. Soil samples were taken for determination of mean weight diameter (MWD), water stable aggregates (WSA), P2O5 content, and organic matter content. Analyses of sediment revealed concentrations of P2O5 and N. All three treatments had significantly different values of MWD (GCV 3.30 mm; TV 2.94 mm; HO 2.16 mm), while WSA and organic matter significantly differs between GCV and HO. The infiltration rate showed no significant difference between treatments. Sediment yield was significantly the highest at the TV (21.01 g kg−1 runoff), while no significant difference was noted between GCV (2.91) and HO (6.59). Sediments of GCV treatment showed higher concentrations of P2O5 and N, compared to TV and HO. Nutrients loss was highest in the TV (450.3 g P2O5 ha−1; 1891.7 g N ha−1) as a result of highest sediment yield, despite the fact GCV had the highest nutrients concentrations. Results indicate that land management (and/or tillage) affects soil properties and their stability. Even tough HO was tilled and had the lowest values of organic matter, WSA, and MWD, measurements were performed immediately after tillage where the plant residues reduced potential erodibility of the soil. Such results reveal that tillage should be avoided in vineyard and hazelnut production in order to prevent soil and nutrient losses.


1999 ◽  
Vol 79 (1) ◽  
pp. 37-45 ◽  
Author(s):  
M. A. Bolinder ◽  
D. A. Angers ◽  
E. G. Gregorich ◽  
M. R. Carter

The response of soil quality attributes to management practices across a diverse range of farming systems is key to identifying a robust minimum data set (MDS). The objectives of this study were to compare the response and consistency of different soil organic matter (SOM) attributes to changes in soil management practices in eastern Canadian agroecosystems. Soil samples (0–10 cm) were obtained at sites of several replicated experiments throughout eastern Canada, and 16 paired comparisons were selected to determine the effect of conservation (no-tillage, rotations, organic amendments) versus conventional (fall moldboard plowing, continuous cropping, no organic amendments) management practices. A sensitivity index was calculated for each of the attributes by dividing the values for conservation treatments with their conventionally managed counterparts (i.e., Conservation/Conventional). The index showed that light fraction (LF) N (1.58) and macro-organic matter-N (MOM-N) (1.54) were the most sensitive SOM attributes to conservation management practices. Light fraction-C (LF-C), macro-organic matter-C (MOM-C) and microbial biomass-C (MB-C) also showed high sensitivity to conservation management (1.48, 1.34 and 1.44, respectively). The sensitivity index for carbohydrates, whole soil C and total N were 1.23, 1.16 and 1.17, respectively. However, the Friedman two-way analysis of variance test indicated that the sensitivity of the different attributes to conservation management was site specific. For example, although LF-N was highly ranked, it did not respond as frequently as most of the other attributes. A non-parametric sign test showed that whole soil C and N provided the most consistent response to conservation management. The average sensitivity index was highest for the amendment (1.82) followed by the tillage (1.26) and rotational (1.14) conservation management practices, suggesting that organic amendments had the greatest impact on most of the attributes. These results suggest that for eastern Canadian soils, use of MOM-C and MOM-N, MB-C and whole soil C would provide a useful, easy to measure and robust MDS. Key words: Soil quality indicators, response, conservation management


2009 ◽  
Vol 89 (3) ◽  
pp. 281-286 ◽  
Author(s):  
Y K Soon ◽  
A Haq ◽  
M A Arshad

The light fraction (LF) has a variable elemental content because it comprises a pool of soil organic matter that is in transition between fresh residues and stable, humified organic matter. Our aim was to assess the influence of time, tillage (CT vs. NT) and straw management (removed or retained) practices on the C and N contents of two particle sizes of LF materials from a Gray Luvisol in Alberta. The LF C and N concentrations were not affected by tillage and straw treatments. The C concentration was higher in LF > 1 mm (coarse LF) than in the < 1 mm LF (fine LF), while the converse was observed for N concentration, resulting in C:N ratios of 45-59 in the coarse fraction and 18-19 for the finer materials. The C concentration of the fine LF decreased and the N concentration increased with time. After 4 yr, LF C and N stocks were higher under NT than under CT mainly because of faster decomposition of litter under CT. Retaining straw resulted in bigger increases in C and N stocks in the coarse LF compared with straw removal; with the fine LF, the C stock decreased more quickly and the N stock increased less rapidly with straw removal. Our results show that time strongly affected the LF C and N stocks and concentrations, and that separating the fraction by size can lead to a more meaningful interpretation of those data.Key words: Light fraction, carbon, nitrogen, tillage, crop residue, straw management


2018 ◽  
Vol 10 (8) ◽  
pp. 341
Author(s):  
Rodrigo Santos Moreira ◽  
Marcio Koiti Chiba ◽  
Isabella Clerici De Maria ◽  
Caio César Zito Siqueira ◽  
Aildson Pereira Duarte ◽  
...  

Soil organic matter is considered a key attribute for a sustainable agricultural production and is influenced by the quantity and quality of the crop residue deposited on the soil surface. Therefore, different crop rotations could change the soil organic matter pools. The objectives of this study were to evaluate the soil carbon pools obtained by chemical and physical fractionation methods and the humification index under different crop rotations in a no-till system. We test the following hypothesis: a) the distribution of C and N among the soil organic matter fractions depends on plant species rotation schemes and; b) labile fractions are more sensitive to the input of crop residues and therefore, more suitable for evaluating the impact of different crop rotations in the soil organic matter quality. We evaluated four crop sequences (corn/corn/corn; corn/wheat/corn; soybean/wheat/corn and soybean/corn/corn) in a no-till system. A five-year reforested area was used as reference. We determined the total C and N contents, the mineral-associated C and N, the light fraction of C and N, the labile carbon extracted with KMnO4 and the soil organic matter humification index. We found narrow differences between the crop rotation systems in the total C and N levels, the mineral-associated C and N fractions and the labile C extracted with KMnO4. The diversification of the agricultural system with soybean in crop rotation favored the accumulation of light fraction C and N in the soil that were more efficient to provide information about the changes in the soil organic matter quality.


Soil Research ◽  
2003 ◽  
Vol 41 (1) ◽  
pp. 95 ◽  
Author(s):  
D. Curtin ◽  
P. M. Fraser

In New Zealand, cereal straw has traditionally been burned to facilitate seedbed preparation for the succeeding crop. Because of concerns over the decline of organic matter and the associated deterioration in soil structure, farmers are interested in incorporating crop residues as a means of maintaining organic matter levels. In a 6-year trial on a Wakanui silt loam on the Canterbury Plains, we evaluated the effects of 3 straw management practices (i.e. straw incorporation, burning of straw, and straw removal) on total and labile soil organic matter. A fourth treatment was included to evaluate the local practice of including seed crops (grass and clover) in cereal rotations. The seed crops were grown every second year, the crop sequence being cereal–ryegrass–cereal–clover–cereal–clover. The rate of straw (wheat) decomposition was determined using a litter bag technique, with the bags being buried at a depth of 15 cm for intervals of up to 19 months. In the straw-incorporated treatment, about 25 t/ha of straw (~11 t C/ha) was returned to the soil during the trial. However, there was no significant effect (P > 0.05) of straw management treatments on total soil C (or N), or on labile organic matter pools, although there was a tendency for higher levels of mineralisable C and N where straw was incorporated. Measured straw decomposition rates were consistent with predictions of the Douglas-Rickman residue decomposition model. Under the relatively warm conditions of the Canterbury Plains (thermal time typically >4000 degree-days per year, calculated as the sum of daily degree-days above a base temperature of 0�C), about three-quarters of incorporated straw decomposed within a year. Of the 11 t C/ha of straw-C incorporated, we estimated that only about 1 t C/ha would remain in the soil at the time of sampling. An increase in soil C by this amount would not be detectable (total soil C was about 55 t/ha in the upper 15 cm). Growing seed crops every second year increased several of the labile organic pools (mineralisable C and N, light fraction C and N, microbial biomass) in the 0–7.5 and 7.5 cm soil layers and this may have beneficial effects (e.g. improved N supply) on the succeeding cereal crop. However, the seed crops did not significantly increase total soil organic matter within the 6 years.


2017 ◽  
Vol 38 (5) ◽  
pp. 2921 ◽  
Author(s):  
Iara Maria Lopes ◽  
Shirlei Almeida Assunção ◽  
Ana Paula Pessim de Oliveira ◽  
Lúcia Helena Cunha dos Anjos ◽  
Marcos Gervasio Pereira ◽  
...  

The gradual change in management practices in sugarcane (Saccharum spp.) production from burning straw to a green harvesting system, as well as the use of minimum soil tillage during field renovation, may affect soil fertility and soil organic matter (SOM) contents. The objectives of this work were to investigate the influence of sugar cane production systems on: (1) soil fertility parameters; (2) on physical carbon fractions; (3) and on humic substance fractions, in a long-term experiment, comparing two soil tillage and two residue management systems an Xanthic Udult, in the coastal tableland region of Espírito Santo State, Brazil. The treatments consisted of plots (conventional tillage (CT) or minimum tillage (MT)) and subplots (residue burned or unburned at harvesting), with five replicates The highest values of Ca2+ + Mg2+ and total organic carbon (TOC) were observed in the MT system in all soil layers, while high values of K+ were observed in the 0.1-0.2 m layer. The CT associated with the burned residue management negatively influenced the TOC values, especially in the 0.1-0.2 and 0.2-0.4 m layers. The carbon in the humin fraction and organic matter associated with minerals were significantly different among the tillage systems; the MT showed higher values than the CT. However, there were no significant differences between the sugarcane residue management treatments. Overall, fractioning the SOM allowed for a better understanding of tillage and residue management systems effects on the soil properties.


1999 ◽  
Vol 79 (3) ◽  
pp. 473-480 ◽  
Author(s):  
S. D. Wanniarachchi ◽  
R. P. Voroney ◽  
T. J. Vyn ◽  
R. P. Beyaert ◽  
A. F. MacKenzie

Agricultural management practices affect the dynamics of soil organic matter (SOM) by influencing the amount of plant residues returned to the soil and rate of residue and SOM decomposition. Total organic C and δ13C of soil were measured in two field experiments involving corn cropping to determine the effect of tillage practices on SOM dynamics. Minimum tillage (MT) and no tillage (NT) had no significant impact on the soil C compared with conventional tillage (CT) in the 0- to 50-cm soil depth sampled at both sites. Continuous corn under MT and CT for 29 yr in a silt loam soil sequestered 61–65 g m−2 yr−1 of corn-derived C (C4-C), and it accounted for 25–26% of the total C in the 0- to 50-cm depth. In a sandy loam soil cropped to corn for 6 yr, SOM contained 10 and 8.4% C4-C under CT and NT, respectively. Reduced tillage practices altered the distribution of C4-C in soil, causing the surface (0–5 cm) soil of reduced tillage (MT and NT) plots to have higher amounts of C4-C compared to CT. Tillage practices did not affect the turnover of C3-C in soil. Key words: Soil organic matter, 13C natural abundance, tillage practices


Soil Research ◽  
2018 ◽  
Vol 56 (8) ◽  
pp. 820 ◽  
Author(s):  
K. A. Conrad ◽  
R. C. Dalal ◽  
D. E. Allen ◽  
R. Fujinuma ◽  
Neal W. Menzies

Quantifying the size and turnover of physically uncomplexed soil organic matter (SOM) is crucial for the understanding of nutrient cycling and storage of soil organic carbon (SOC). However, the C and nitrogen (N) dynamics of SOM fractions in leucaena (Leucaena leucocephala)–grass pastures remains unclear. We assessed the potential of leucaena to sequester labile, free light fraction (fLF) C and N in soil by estimating the origin, quantity and vertical distribution of physically unprotected SOM. The soil from a chronosequence of seasonally grazed leucaena stands (0–40 years) was sampled to a depth of 0.2m and soil and fLF were analysed for organic C, N and δ13C and δ15N. On average, the fLF formed 20% of SOC and 14% of total N stocks in the upper 0.1m of soil from leucaena rows and showed a peak of fLF-C and fLF-N stocks in the 22-year-stand. The fLF δ13C and fLF δ15N values indicated that leucaena produced 37% of fLF-C and 28% of fLF-N in the upper 0.1m of soil from leucaena rows. Irrespective of pasture type or soil depth, the majority of fLF-C originated from the accompanying C4 pasture-grass species. This study suggests that fLF-C and fLF-N, the labile SOM, can form a significant portion of total SOM, especially in leucaena–grass pastures.


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