Study

Management options to decrease phosphorus and sediment losses from irrigated cropland grazed by cattle and sheep

  • Published source details McDowell R.W. & Houlbrooke D.J. (2009) Management options to decrease phosphorus and sediment losses from irrigated cropland grazed by cattle and sheep. Soil Use and Management, 25, 224-233.

Actions

This study is summarised as evidence for the following.

Action Category

Amend the soil with non-chemical minerals and mineral wastes

Action Link
Soil Fertility

Reduce grazing intensity

Action Link
Soil Fertility

Amend the soil with formulated chemical compounds

Action Link
Soil Fertility
  1. Amend the soil with non-chemical minerals and mineral wastes

    This controlled, replicated experiment in 2004-2008 on silt loam soil in New Zealand (McDowell & Houlbrooke 2009) found that applying alum (aluminium sulphate) after grazing of forage crops by cattle or sheep reduced phosphorus loss by 29% and 26%, and fine sediment loss by 16% and 43%, respectively, compared to normal forage crop grazing. Grazing cattle or sheep on forage crops increased phosphorus loss from fields by approximately 100% (1.3 kg/ha) and 33% (0.9 kg/ha) respectively, compared to normal sheep grazing on pasture (0.6 kg/ha).  Forage grazing by cattle or sheep increased fine sediment loss by 1,000% (0.7 mg/ha) and 500% (0.4 mg/ha), relative to grazing pasture with sheep (0.06 mg/ha). Twenty-eight 10 × 25 m plots included four replicates of combinations of the following treatments: cattle or sheep grazing on winter forage crops (triticale Triticosecale Wittmack, then kale Brassica oleracea), sheep pasture, restricted grazing, or alum addition on the forage crops (20 kg/ha following grazing).

     

  2. Reduce grazing intensity

    A controlled, replicated experiment in 2004-2008 on silt loam soil in New Zealand (McDowell & Houlbrooke 2009) found that phosphorus loss from forage crop fields was reduced by 26% and 36%, and sediment loss by 35% and 53%, when cattle and sheep grazing was reduced to three/hours a day. Grazing cattle or sheep on forage crops increased phosphorus loss by approximately 100% (1.3 kg/ha) and 33% (0.9 kg/ha) respectively, relative to grazing sheep on pastures (0.6 kg/ha).  Cattle or sheep grazing increased the amount of fine sediment washed from fields by 1,000% (0.7 mg/ha) or 500% (0.4 mg/ha), compared to grazing sheep on pastures (0.06 mg/ha). There were 28 plots (10 × 25 m) testing combinations of the following treatments: cattle or sheep grazing on winter forage crops (triticale Triticosecale Wittmack, then kale Brassica oleracea), sheep grazing on pasture, restricted grazing, and/or alum addition (20 kg/ha following grazing). Treatments were replicated four times.

     

  3. Amend the soil with formulated chemical compounds

    This controlled, replicated experiment in 2004-2008 on silt loam soil in New Zealand (McDowell & Houlbrooke 2009) found that applying alum (aluminium sulphate) after grazing of forage crops by cattle or sheep reduced phosphorus loss by 29% and 26%, and fine sediment loss by 16% and 43%, respectively, compared to normal forage crop grazing. Grazing cattle or sheep on forage crops increased phosphorus loss from fields by approximately 100% (1.3 kg/ha) and 33% (0.9 kg/ha) respectively, compared to normal sheep grazing on pasture (0.6 kg/ha).  Forage grazing by cattle or sheep increased fine sediment loss by 1,000% (0.7 mg/ha) and 500% (0.4 mg/ha), relative to grazing pasture with sheep (0.06 mg/ha). Twenty-eight 10 × 25 m plots included four replicates of combinations of the following treatments: cattle or sheep grazing on winter forage crops (triticale Triticosecale Wittmack, then kale Brassica oleracea), sheep pasture, restricted grazing, or alum addition on the forage crops (20 kg/ha following grazing).

     

Output references
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