Influence of organic waste amendments on selected soil physical and chemical properties

1999 ◽  
Vol 79 (3) ◽  
pp. 501-504 ◽  
Author(s):  
B. J. Zebarth ◽  
G. H. Neilsen ◽  
E. Hogue ◽  
D. Neilsen

Sandy, infertile soils can benefit from the addition of organic waste amendments. Annual applications of organic wastes for as long as 4 yr increased soil organic matter content, decreased soil bulk density, and increased soil water retention of a coarse-textured soil. However, soil water-holding capacity was not necessarily increased, and there was a limited effect on soil cation exchange capacity. Key words: Cation exchange capacity, water retention, soil pH, soil organic matter, soil bulk density

Solid Earth ◽  
2017 ◽  
Vol 8 (4) ◽  
pp. 827-843 ◽  
Author(s):  
Sunday Adenrele Adeniyi ◽  
Willem Petrus de Clercq ◽  
Adriaan van Niekerk

Abstract. Cocoa agroecosystems are a major land-use type in the tropical rainforest belt of West Africa, reportedly associated with several ecological changes, including soil degradation. This study aims to develop a composite soil degradation assessment index (CSDI) for determining the degradation level of cocoa soils under smallholder agroecosystems of southwestern Nigeria. Plots where natural forests have been converted to cocoa agroecosystems of ages 1–10, 11–40, and 41–80 years, respectively representing young cocoa plantations (YCPs), mature cocoa plantations (MCPs), and senescent cocoa plantations (SCPs), were identified to represent the biological cycle of the cocoa tree. Soil samples were collected at a depth of 0 to 20 cm in each plot and analysed in terms of their physical, chemical, and biological properties. Factor analysis of soil data revealed four major interacting soil degradation processes: decline in soil nutrients, loss of soil organic matter, increase in soil acidity, and the breakdown of soil textural characteristics over time. These processes were represented by eight soil properties (extractable zinc, silt, soil organic matter (SOM), cation exchange capacity (CEC), available phosphorus, total porosity, pH, and clay content). These soil properties were subjected to forward stepwise discriminant analysis (STEPDA), and the result showed that four soil properties (extractable zinc, cation exchange capacity, SOM, and clay content) are the most useful in separating the studied soils into YCP, MCP, and SCP. In this way, we have sufficiently eliminated redundancy in the final selection of soil degradation indicators. Based on these four soil parameters, a CSDI was developed and used to classify selected cocoa soils into three different classes of degradation. The results revealed that 65 % of the selected cocoa farms are moderately degraded, while 18 % have a high degradation status. The numerical value of the CSDI as an objective index of soil degradation under cocoa agroecosystems was statistically validated. The results of this study reveal that soil management should promote activities that help to increase organic matter and reduce Zn deficiency over the cocoa growth cycle. Finally, the newly developed CSDI can provide an early warning of soil degradation processes and help farmers and extension officers to implement rehabilitation practices on degraded cocoa soils.


2016 ◽  
Vol 47 (sup1) ◽  
pp. 75-89 ◽  
Author(s):  
Jorge Paz Ferreiro ◽  
Vicente Pereira De Almeida ◽  
Marlene Cristina Alves ◽  
Cleide Aparecida De Abreu ◽  
Sidney R. Vieira ◽  
...  

SOIL ◽  
2016 ◽  
Vol 2 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Alemayehu Adugna ◽  
Assefa Abegaz

Abstract. Land use change can have negative or positive effects on soil quality. Our objective was to assess the effects of land uses changes on the dynamics of selected soil physical and chemical properties. Soil samples were collected from three adjacent soil plots under different land uses, namely forestland, grazing land, and cultivated land at 0–15 cm depth. Changes in soil properties on cultivated and grazing land were computed and compared to forestland, and ANOVA (analysis of variance) was used to test the significance of the changes. Sand and silt proportions, soil organic content, total nitrogen content, acidity, cation exchange capacity, and exchangeable Ca2+ content were higher in forestlands. Exchangeable Mg2+ was highest in grazing land, while clay, available phosphorous, and exchangeable K+ were highest in cultivated land. The percentage changes in sand, clay, soil organic matter, cation exchange capacity, and exchangeable Ca2+ and Mg2+ were higher in cultivated land than in grazing land and forestland. In terms of the relation between soil properties, soil organic matter, total nitrogen, cation exchange capacity, and exchangeable Ca2+ were strongly positively correlated with most of soil properties, while available phosphorous and silt have no significant relationship with any of the other considered soil properties. Clay has a negative correlation with all soil properties. Generally, cultivated land has the least concentration of soil physical and chemical properties except clay and available phosphorous, which suggests an increasing degradation rate in soils of cultivated land. So as to increase soil organic matter and other nutrients in the soil of cultivated land, the integrated implementation of land management through compost, cover crops, manures, minimum tillage, crop rotation, and liming to decrease soil acidity are suggested.


Soil Research ◽  
2015 ◽  
Vol 53 (4) ◽  
pp. 377 ◽  
Author(s):  
D. Curtin ◽  
P. M. Fraser ◽  
M. H. Beare

Cultivation of grassland is known to lead to the depletion of soil organic matter (SOM), but the effect on the size and composition of the exchangeable cation suite has not been documented. We measured cation exchange capacity (CEC) and exchangeable cations (calcium, Ca; magnesium, Mg; potassium, K; sodium, Na), as well as soil carbon (C) and nitrogen (N) (0–7.5, 7.5–15, and 15–25 cm), 8 years after conversion of long-term ryegrass–white clover pasture (grazed by sheep) to annual crop production. The trial was near Lincoln, Canterbury, New Zealand. The trial included three tillage treatments: crops established using intensive cultivation (mouldboard ploughing), minimum tillage (shallow cultivation, ~10 cm), or no-tillage. The 8-year rotation was barley, wheat, pea, barley, pea, barley, barley, barley. A sheep-grazed pasture was maintained as an experimental control. The experiment also included a permanent fallow treatment (maintained plant-free using herbicides; not cultivated). After 8 years under arable cropping, soil C stocks (0–25 cm) were 10 t ha–1 less, on average, than under pasture. The vertical distribution of soil organic matter (SOM) was affected by tillage type, but the total amount of organic matter in the top 25 cm did not differ (P > 0.05) among the tillage treatments. Under permanent fallow (C loss of 13 t ha–1 relative to pasture), total exchangeable cation (Ca + Mg + K +Na) equivalents declined by 47 kmolc ha–1, a 20% decrease compared with pasture. Loss of exchange capacity resulted in the selective release of cations with lower affinity for SOM (K, Na, Mg). Smaller losses of exchangeable cations were recorded under the arable cropping rotation (average 31 kmolc ha–1), with no differences among tillage treatments. Effective CEC (at field pH) decreased under permanent fallow and cultivated treatments because of: (1) depletion of SOM (direct effect); and (2) soil acidification, which eliminated some of the remaining exchange sites (indirect effect). Acidification in the permanent fallow can be attributed to the N mineralisation process, whereas in the cropped systems, excess cation removal in harvested straw and grain accounted for about half of the measured acidification. There was evidence that the organic matter lost under arable cropping and fallow had lower CEC than SOM as a whole.


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