Study

Organic carbon and total nitrogen stocks in a Vertisol following 40 years of no-tillage, crop residue retention and nitrogen fertilisation

  • Published source details Dalal R.C., Allen D.E., Wang W.J., Reeves S. & Gibson I. (2011) Organic carbon and total nitrogen stocks in a Vertisol following 40 years of no-tillage, crop residue retention and nitrogen fertilisation. Soil and Tillage Research, 112, 133-139.

Actions

This study is summarised as evidence for the following.

Action Category

Retain crop residues

Action Link
Soil Fertility

Amend the soil with formulated chemical compounds

Action Link
Soil Fertility

Change tillage practices

Action Link
Soil Fertility
  1. Retain crop residues

    A randomized, replicated experiment from 1968 to 2008 on clay soil in Australia (Dalal et al. 2011) found higher soil organic carbon when crop residues were retained (20.5 Mg/ha) rather than burned (19.5 Mg/ha) in the topsoil. Crop residue retention only affected carbon levels when fertilizer was also applied (1.8 Mg C/ha more carbon with residues and a high fertilizer application rate, compared to no residue and no fertilizer). Nitrogen was 125 kg N/ha higher with retained residues than when burned and total soil nitrogen increased with fertilizer rate when residues were retained. Average grain yield was higher when crop residue was retained under no-tillage plus 90 kg N/ha/year (2.9 Mg/ha) compared to retaining residue under conventional tillage without fertilizer (2.3 Mg/ha). Wheat Triticum aestivum was the principle crop bar three years which were cropped with barley Hordeum vulgare. Treatments included: tillage (conventional tillage to 10 cm depth vs. no-tillage), crop residue management (burned or retained), and nitrogen fertilizer application (none, low (30 kg N/ha/year)  or high (90 kg) application). Plots were 61.9 x 6.4 m and treatments were replicated four times. Soil was sampled in each plot at the end of the experiment to 1.5 m depth.

     

  2. Amend the soil with formulated chemical compounds

    A randomized, replicated experiment from 1968 to 2008 on clay soil in Australia (Dalal et al. 2011) found soil organic carbon was highest under high (20.40 Mg/ha), then medium (20.13 Mg/ha), compared to no nitrogen application (19.53 Mg/ha), in the topsoil. Fertilizer application only affected carbon levels when crop residue was retained, (1.8 Mg C/ha more carbon under high fertilizer with residues retained, compared to no fertilizer no residue).  Nitrogen was 125 kg N/ha higher under high fertilizer application compared to no fertilizer. Total soil nitrogen increased with nitrogen fertilizer application only when crop residues were retained. Average grain yield was highest under no-tillage plus crop residue and high fertilizer (2.86 Mg/ha) and lowest under conventional tillage plus crop residue, no fertilizer (2.28 Mg/ha). Wheat Triticum aestivum was the principle crop bar three years which were cropped with barley Hordeum vulgare. Treatments included: tillage (conventional tillage 10 cm depth, no-tillage); crop residue management (burned or retained); and nitrogen fertilizer application (none applied, low or high application (30 and 90 kg N/ha/year respectively). Plots were 61.9 x 6.4 m and replicated four times. Soil was sampled in each plot at the end of the experiment to 1.5 m depth.

  3. Change tillage practices

    A randomized, replicated experiment from 1968 to 2008 on clay soil in Queensland, Australia (Dalal et al. 2011) found higher soil organic carbon under no-tillage (20.21 Mg/ha) compared with conventional tillage (19.83 Mg/ha). Total soil nitrogen was not affected by tillage treatment. Average grain yield was highest under no-tillage when crop residue was retained (2.86 Mg/ha) with high fertilizer application, and lowest under conventional tillage when crop residue was retained (2.28 Mg/ha) with no fertilizer. This 40- year experiment was cropped with wheat Triticum aestivum except for three years which were cropped with barley Hordeum vulgare and had the following treatments: tillage (conventional tillage (3-4 times to 10 cm depth), no-tillage); crop residue management (residue burned, residue retained); and nitrogen fertilizer application (none applied, 30 kg N/ha/year (low), and 90 kg N/ha/year (high), applied at sowing). Plots were 61.9 x 6.4 m and were replicated four times. Five soil samples were taken from each plot at the end of the experiment (May 2008) to 1.5 m depth.

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