Careful management of drought-affected pastures after rain

// Pasture and Crops

As drought-ravaged pastures respond to moisture it is important farmers resist the temptation to graze any green growth and allow the plants to build root reserves.

This was message Farm Systems scientist Tom Fraser gave farmers at a recent B+LNZ Farming for Profit field day in Canterbury.

Any green growth after rain means the plant is photosynthesizing and root reserves depleted during the drought will be being built up again. This is especially important going into winter as those reserves will be essential to drive pasture growth in spring.

Grazing pastures too soon after rain could deplete root reserves even further and lead to the death of the plant.

Tom says spring forage supply is most critical and while farmers in many parts of the country are struggling with limited feed resources due to drought, the way pastures are managed in autumn will determine spring growth.

He says by mid-April it is possible to determine what spring growth will be.

“The more leaves those plants have the better spring growth will be.”

He says after rain, farmers need to stay in drought-mode for two to three weeks.

“The worst thing you can do for both plant and animals is graze green-tinged pastures, just stay off it.”

Short pastures can pose internal parasite and Facial Eczema risks to livestock.

Tom recommends farmers rank their pastures on a one to four scale (one being terrible and four not too bad) and treat the better pastures with kid-gloves over winter. They should be the last to be grazed in autumn and a dressing of nitrogen (N) could be considered.

“N applied from the end March through April, provided soil temperatures remain above 7-8 degrees celsius in the top 10cm of soil and the pasture is actively growing, will help push feed forward into winter even though the response to the N may be small.”

He says farmers need to leave at least three weeks, but preferably longer, between application and grazing to maximise the response.

N applied in autumn helps grass plants produce new tillers which will grow in spring. Some of the N taken up by the plant may be stored in roots and can help the plant kick off in the spring.

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