Application of organic amendments to a coastal saline soil in north China: effects on soil physical and chemical properties and tree growth

Abstract

The ability of the following four organic amendments to ameliorate saline soil in coastal northern China was investigated from April 2010 to October 2012 in a field experiment: green waste compost (GWC), sedge peat (SP), furfural residue (FR), and a mixture of GWC, SP and FR (1∶1∶1 by volume) (GSF). Compared to a non-amended control (CK), the amendments, which were applied at 4.5 kg organic matter m(-3), dramatically promoted plant growth; improved soil structure; increased the cation exchange capacity (CEC), organic carbon, and available nutrients; and reduced the salt content, electrical conductivity (EC), and exchangeable sodium percentage (ESP). At the end of the experiment in soil amended with GSF, bulk density, EC, and ESP had decreased by 11, 87, and 71%, respectively, and total porosity and organic carbon had increased by 25 and 96% respectively, relative to the CK. The GSF treatment resulted in a significantly lower Na(+)+K(+) content than the other treatments. CEC and the contents of available N, P, and K were significantly higher in the GSF-treated soil than in the CK and were the highest in all treatments. The FR treatment resulted in the lowest pH value and Ca(2+) concentration, which decreased by 8% and 39%, respectively, relative to the CK. Overall, the results indicate that a combination of green waste compost, sedge peat and furfural residue (GSF treatment) has substantial potential for ameliorating saline soils in the coastal areas of northern China, and it works better than each amendment alone. Utilization of GWC and FR can be an alternative organic amendment to substitute the nonrenewable SP in saline soil amelioration.

Figure 1. Effects of organic amendments on (A) bulk density, (B) total porosity, (C) electrical conductivity (EC), and (D) exchangeable sodium percentage (ESP) in saline soil.

CK, non-amended control; GWC, green waste compost; SP, sedge peat; FR, furfural residue; GSF, green waste compost plus sedge peat plus furfural residue. Rates are indicated in the text but all amendments provided 4.5 kg of organic matter m⁻³. Treatments were applied in April 2010, and samples were collected in October 2010, October 2011, and October 2012. Values are means+SEMs. Means in the same year followed by the same letter are not significantly different at p≤0.05 according to LSD.

Figure 2. Effects of organic amendments on (A) soil pH, (B) soil organic carbon, (C) cation exchange capacity (CEC), (D) available N, (E) available P, and (F) available K in saline soil.

CK, non-amended control; GWC, green waste compost; SP, sedge peat; FR, furfural residue; GSF, green waste compost plus sedge peat plus furfural residue. Rates are indicated in the text but all amendments provided 4.5 kg of organic matter m⁻³. Treatments were applied in April 2010, and samples were collected in October 2010, October 2011, and October 2012. Values are means+SEMs. Means in the same year followed by the same letter are not significantly different at p≤0.05 according to LSD.

Figure 3. Effects of organic amendments on Pagoda tree (Sophora japonica Linn) (A) tree height, and (B) basal diameter in saline soil.

CK, non-amended control; GWC, green waste compost; SP, sedge peat; FR, furfural residue; GSF, green waste compost plus sedge peat plus furfural residue. Rates are indicated in the text but all amendments provided 4.5 kg of organic matter m⁻³. Treatments were applied in April 2010, and data was determined in October 2010, October 2011, and October 2012. Values are means+SEMs. Means in the same year followed by the same letter are not significantly different at p≤0.05 according to LSD.