Monitoring Variability in Peas

Peas are one crop that has huge variation. It’s hard to know if the crop will yield four tonnes per hectare or twelve. Even within small sampling plots we measured yields less than 4 t/ha and greater than 13 t/ha.

Our peas were planted into wet soil and had cold weather afterwards. Then they were savaged by pigeons. So right from the start there was variation. There were bald patches, slow germinating plants and plants with growing tips nipped out.

Counting the number of peas in 1m2 to assess paddock population. Repeating measurements shows variability.
Counting the number of peas in 1m2 to assess paddock population. Comparing repeated measurements allows statistical variability to be calculated.

We put some cover cloth over plants and observed different growth. After three weeks we removed the covers and could see difference. We got a sensor that measures ground cover and compared covered and uncovered areas. There was as much as 50% difference with covered plants much bigger. We think some of the difference is pigeon related. But maybe the covers also have other effects.

After crop cover was removed, greater growth and fuller ground cover was obvious
After crop cover was removed, greater growth and fuller ground cover was obvious

We visited a number of pea crops in Central Hawke’s Bay. We saw the same variability in young crops and old. The rate of maturation is critical for vining peas as they have to peak the day (hour?) they are harvested. We’ve identified condensed flowering as a target for pea crops. We want flowering to start and stop in a short period, and pods to fill evenly to be similar maturity for harvest. In variable paddocks (uneven soils, dry areas) flowering can start and finish at different times. A long period means later pods will still be filling while the first are already getting past their prime.

This crop shows areas of delayed and advanced flowering. All is to be harvested at the same time so some will be ready and some not.
This crop shows areas of delayed and advanced flowering. All is to be harvested at the same time so some will be ready and some not.

We had cool conditions at the MicroFarm and think this extended the flowering period. We could see pods filling while new flowers were starting to bloom.

Variation occurs on a single plant when long flowering times see pods filling while new flowers are opening.
Variation occurs on a single plant when long flowering times see pods filling while new flowers are opening.

The variability is a problem at harvest. Setting beater speed is a difficult task when the TR range is wide; hard enough to get tougher pods open yet soft enough to save the tenderest young peas. The problem is very obvious then, but it started long ago.

Peas taken and hand sorted from a single sample from the harvester - those on the left are mature, those on the right too young and damaged.
Peas taken and hand sorted from a single sample from the harvester – those on the left are mature, those on the right too young and damaged.

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