Machine Harvesting of Lima Beans for Processing

ABSTRACT

Pod stripper combines are the predominant method of harvesting lima beans for processing in the Mid-Atlantic region. Losses during harvest represent a significant economic loss to growers and processors. Eighty-four field tests in 1994 and 1995 showed that total crop loss during harvest averaged more than 540 kg/ha (475 lbs/acre) or 23.6% of the commercial yield. Results for four baby lima bean varieties and combines from five different manufacturers indicate the major field loss occurs at the header of the combine where the pods are stripped from the plant. Threshing and cleaning losses on the combine averaged less than 25% of the total crop loss. The cultivar ‘Maffei 15’ exhibited significantly higher header loss than the variety ‘8–78.’ There were no significant differences in loss between any of the combines evaluated. The predominant losses occurring at the combine header were loose pods and pods left on the plant. Trash content in the harvested beans averaged 13% by weight.

Field levelness across the width of the combine header significantly affected header loss. Unlevel ground conditions resulting from mechanical cultivation for weed control doubled the amount of header loss compared to level ground conditions. Excessive cultivator ground speed, multiple cultivator passes and improper cultivator configuration will each contribute to the unlevel ground conditions which lead to significantly higher losses at the combine header. Weed control programs which incorporate cultivation practices that result in minimal ground disturbance and leave a level soil surface will help maximize lima bean recovery with pod stripper combines. The results verify that certain lima bean varieties are better suited than others for mechanical harvesting with pod stripper combines. Additional research is needed to quantify and improve the properties of lima bean plants that can enhance their mechanical harvesting characteristics.

KEYWORDS:

• Lima bean
• mechanical harvesting
• pod-stripper combine
• field loss