Academia.eduAcademia.edu

Figure 4 – uploaded by Johan Six

See full PDFdownloadDownload figure
Parameter estimates from four selected models fitting the aggregate formation data of a silty loam soil after addition of 1.5 g wheat residue 100 g~! soil over time (Fig. 5) and the aggregate formation data of three different soils and six different residue additions (between 0 and 3 g residue 100 g~' soil) after 3 weeks of incubation (Fig. 3) Values are mean = standard error. a ‘ eh é F Due to the constrained optimization procedure, no error data was available.

Figure 5 Parameter estimates from four selected models fitting the aggregate formation data of a silty loam soil after addition of 1.5 g wheat residue 100 g~! soil over time (Fig. 5) and the aggregate formation data of three different soils and six different residue additions (between 0 and 3 g residue 100 g~' soil) after 3 weeks of incubation (Fig. 3) Values are mean = standard error. a ‘ eh é F Due to the constrained optimization procedure, no error data was available.

Related Figures (8)

OC, organic carbon. General properties of the soils used in the two incubation experiments Table 1
OC, organic carbon. General properties of the soils used in the two incubation experiments Table 1
Fig. 1. Respiration of a silty clay loam soil during a three week incubation after addition of a range of organic residue amounts (between 0 and 3 g residue 100 g_! soil). Values are means + standard error.
Fig. 1. Respiration of a silty clay loam soil during a three week incubation after addition of a range of organic residue amounts (between 0 and 3 g residue 100 g_! soil). Values are means + standard error.
Slope and intercepts from simple linear regressions between cumulative respiration, water-stable macroaggregation and fungal lengths vs organic matter addition, of three different soils and six different residue additions (between 0 and 3 g residue 100 g~! soil) after 3 weeks of incubation
Slope and intercepts from simple linear regressions between cumulative respiration, water-stable macroaggregation and fungal lengths vs organic matter addition, of three different soils and six different residue additions (between 0 and 3 g residue 100 g~! soil) after 3 weeks of incubation
Fig. 2. Total cumulative respiration of three different soils and six different residue additions (between 0 and 3 g residue 100g”! soil) after 3 weeks of incubation. Within an organic matter addition treatment, bars with a different lowercase letter differ significantly among soils (P<0.05).
Fig. 2. Total cumulative respiration of three different soils and six different residue additions (between 0 and 3 g residue 100g”! soil) after 3 weeks of incubation. Within an organic matter addition treatment, bars with a different lowercase letter differ significantly among soils (P<0.05).
Fig. 3. Aggregation of three different soils and six different residue additions (between 0 and 3 gresidue 100 g_' soil) after 3 weeks of incubation and aggregation of the three soils in the field. Within an organic matter addition treatment, bars with a different lowercase letter differ significantly among soils (P<0.05).
Fig. 3. Aggregation of three different soils and six different residue additions (between 0 and 3 gresidue 100 g_' soil) after 3 weeks of incubation and aggregation of the three soils in the field. Within an organic matter addition treatment, bars with a different lowercase letter differ significantly among soils (P<0.05).
Fig. 4. Fungal lengths of three different soils and six different residue additions (between 0 and 3 g residue 100 g~' soil) after 3 weeks of incubation. Within a organic matter addition treatment, bars with a different lowercase letter differ significantly among soils (P <0.05). Fungal lengths increased with increasing amounts of residue added (Fig. 4) in the sandy soil from 5.2+0.5 m g7! in the control to 67.8+1.7mg! in the 3% addition treatment. The slope of the regression between fungal hyphae length and residue addition rate was 20+ 2.8. In the silt loam, soil fungal hyphae lengths increased from 1.6+0.3 mg”! in the control to 20.0+4.4m g™! in the 3% addition treatment; the slope was 6.3 + 1.2. The silty clay loam soil showed no clear increase in fungal hyphae lengths with increasing amounts of residue added, the regression between these two factors was not significant (Table 2). In all treatments with residue added, t he hyphal length in the sandy soil was significantly larger than the hyphal lengths of the silt loam and the silty clay oam soil. With the addition of 3% of residue added, hyphal lengths were Statistically different across the three soils (67.8+1.7mg_' for the sandy loam, 20.0+4.4mg ! for the silt loam and 7.9+0.6 m g~! in the silty c ay loam).
Fig. 4. Fungal lengths of three different soils and six different residue additions (between 0 and 3 g residue 100 g~' soil) after 3 weeks of incubation. Within a organic matter addition treatment, bars with a different lowercase letter differ significantly among soils (P <0.05). Fungal lengths increased with increasing amounts of residue added (Fig. 4) in the sandy soil from 5.2+0.5 m g7! in the control to 67.8+1.7mg! in the 3% addition treatment. The slope of the regression between fungal hyphae length and residue addition rate was 20+ 2.8. In the silt loam, soil fungal hyphae lengths increased from 1.6+0.3 mg”! in the control to 20.0+4.4m g™! in the 3% addition treatment; the slope was 6.3 + 1.2. The silty clay loam soil showed no clear increase in fungal hyphae lengths with increasing amounts of residue added, the regression between these two factors was not significant (Table 2). In all treatments with residue added, t he hyphal length in the sandy soil was significantly larger than the hyphal lengths of the silt loam and the silty clay oam soil. With the addition of 3% of residue added, hyphal lengths were Statistically different across the three soils (67.8+1.7mg_' for the sandy loam, 20.0+4.4mg ! for the silt loam and 7.9+0.6 m g~! in the silty c ay loam).
Parameters from regression analysis between microbial parameters (cumulative respiration and fungal lengths) and aggregation, of three different soils and six different residue additions (between 0 and 3 g residue 100 g~! soil) after 3 weeks of incubation r is Pearson’s product-momentum correlation coefficient, P is the significance of the correlation and n is the number of observations used in the correlation. * indicates a significant difference (P<0.05) in the correlation coefficient between cumulative respiration versus water-stable macroaggregation and fungal length versus water-stable aggregation.
Parameters from regression analysis between microbial parameters (cumulative respiration and fungal lengths) and aggregation, of three different soils and six different residue additions (between 0 and 3 g residue 100 g~! soil) after 3 weeks of incubation r is Pearson’s product-momentum correlation coefficient, P is the significance of the correlation and n is the number of observations used in the correlation. * indicates a significant difference (P<0.05) in the correlation coefficient between cumulative respiration versus water-stable macroaggregation and fungal length versus water-stable aggregation.
The increase in water-stable macroaggregates of the silty loam soil after an addition of 1.5% of residue was largest between days 3 and 9 (Fig. 5). After day 15, the formation rate decreased. The ability of four simple models to predict aggregate formation was tested using the aggregation over time data. Parameter values for the four models are summarized in Table 4. The four models performed equally well as their adjusted R? were similar (around 0.85). Moreover, the goodness of fit F-test was significant at P<0.0001 for all four models. The linear model revealed that aggregate formation occurred at a constant rate of 0.65+0.06% day '. However, the residuals were not When the three soils were considered amounts of macroaggregates were significant separately, y correlated with both cumulative respiration and fungal length (Table 3), except for the silty clay loam soil in which fungal lengths were significantly less correlated with water- stable macroaggregates than for the other soils. There was no significant difference between correlations o f cumulative respiration versus water-stable macroaggregation and fun- gal length versus water-stable macroaggregation, except for the silty clay loam soil in which cumulative res piration was a better predictor for water-stable macroaggregation than fungal length. Combining all three soils toge ther yielded significant correlations between water-stable macroaggre- gation and cumulative respiration or fungal length. However, these correlations were less good than for the single soils. Furthermore, combining all three soils, Fig. 5. Water-stable macroaggregation of the silty loam soil during a 3 week incubation after addition of 1.5 g wheat residue 100 g~! of soil (mean+standard error). The data is fitted using four different models: linear, sigmoidal, exponential rise to maximum, and a model in which aggregate formation is proportional to respiration.
The increase in water-stable macroaggregates of the silty loam soil after an addition of 1.5% of residue was largest between days 3 and 9 (Fig. 5). After day 15, the formation rate decreased. The ability of four simple models to predict aggregate formation was tested using the aggregation over time data. Parameter values for the four models are summarized in Table 4. The four models performed equally well as their adjusted R? were similar (around 0.85). Moreover, the goodness of fit F-test was significant at P<0.0001 for all four models. The linear model revealed that aggregate formation occurred at a constant rate of 0.65+0.06% day '. However, the residuals were not When the three soils were considered amounts of macroaggregates were significant separately, y correlated with both cumulative respiration and fungal length (Table 3), except for the silty clay loam soil in which fungal lengths were significantly less correlated with water- stable macroaggregates than for the other soils. There was no significant difference between correlations o f cumulative respiration versus water-stable macroaggregation and fun- gal length versus water-stable macroaggregation, except for the silty clay loam soil in which cumulative res piration was a better predictor for water-stable macroaggregation than fungal length. Combining all three soils toge ther yielded significant correlations between water-stable macroaggre- gation and cumulative respiration or fungal length. However, these correlations were less good than for the single soils. Furthermore, combining all three soils, Fig. 5. Water-stable macroaggregation of the silty loam soil during a 3 week incubation after addition of 1.5 g wheat residue 100 g~! of soil (mean+standard error). The data is fitted using four different models: linear, sigmoidal, exponential rise to maximum, and a model in which aggregate formation is proportional to respiration.
Related topics:
Soil Aggregation
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved