From the literature it appears that in the developing countries, crop harvesting equipment available with the smallholder farmers have changed very little over the years. The search for more efficient, cost-effective ways of harvesting and threshing the crop is significant because of the extreme labour intensity of these tasks. For example, up to 40 percent of the total labour required to grow this crop is expended in harvesting operations. At peak harvest periods labour shortages often occur, even in regions that normally have surplus labour available. This can either lead to higher costs of production or reduced yields. Several factors other than capital costs affect decisions on using harvesting and threshing equipment. The size of the farm in physical and economic terms influences the scale of machinery and the appropriate investment. If only a small amount of work is undertaken each season, then the capital cost per unit of work done may be so high that a machine may not be economical compared to alternative methods. Trade-offs can be avoided where multi-farm equipment use is possible, but this approach requires a high degree of organization and cooperation, especially when timely harvesting is critical.

 Figure 4: Manual harvesting and lifting of Spanish type of groundnut by hired labourers.

In bunch types, pod development is confined to the base of the plant and the pegs carrying the pods into the soil are thick and strong. Almost all the pods are recovered with the plants when they are pulled out of the soil (Figure 4). The bunch type of groundnut is mostly harvested by pulling out the plants with manual labour in India. The diversity of the labour employed to harvest the crop depends on the location. For instance male labourers are used in Tamil Nadu and in Gujarat both male and female labourers are employed. Usually 12 to 14 labourers can harvest one-hectare area of groundnut crop in one day.

Harvesting may sometimes become a problem especially when the crop has passed the stage of full maturity and the soil has hardened. In this case, it is customary to lift the plants by loosening the soil either by working a hand hoe, a plough or a blade harrow along the plant rows. If after lifting the crop manually it is observed that a good percentage of the pods have been left in the soil, the same implements may be used to pick the leftover pods. In the latter case, additional labour will be required. In the case of the spreading type, the process of up-rooting the crop from the soil is a rather difficult operation as pod formation takes place all along the creeping branches of the plant. The pegs are comparatively thinner and more delicate. In Figure 5. a blade type digger is harvesting a runner type of groundnut (Figure 5).

 Figure 5: Groundnut harvesting by a blade type digger being operated by bullocks and tractor.

As compared to manual uprooting, the performance of the bullock-drawn digger is satisfactory and economical. The digger lifts groundnut plants from a depth of 10 to 12 cm. Several models are available in the markets to be operated either by the animal draught or by the power tiller drive (3 to 6 hp). The capacity of various diggers ranges from 1.2 ha h^-1 (animal drawn) to 1.5 ha h^-1 (power tiller).

Harvesting bottlenecks in the less-developed regions are commonly caused by the logistics of lifting plants from the ground. This task is the most mechanized operation in developed countries and replaces the hard manual labour of digging. Many models of ploughs or digger blades can be used to up-root one or several rows. The design depends on whether the digger is animal operated or mechanically powered. It is essential that the blade or ploughshare be set deep enough to cut below all the pods, but not so deep as to increase draughts unnecessarily. Slow speeds and additional implements are preferable to higher speeds with fewer tools, especially when kernels are produced for table consumption. The gain in yield, quality and final price offsets the additional digging costs. Harvesting techniques can also affect milling quality of groundnuts. Sweeps or fingers may be necessary on the digging blades to ensure that the plants are left well to one side of the opened furrow and not covered with soil. Where it is necessary to combine several rows of plants into one, this operation must be carried out soon after lifting as practicable or pod loss can occur. Raking early in the day when plants are moist reduces this danger.

In certain areas, the vines are uprooted with country ploughs and the vines and pods are picked by manual labour (Figure 6). The pods left over in the soil are picked by hand. Groundnut diggers drawn by a pair of bullocks or by tractor are available in market. The bullock-drawn groundnut digger can harvest groundnut crops over an area of 0.75 hectares in 8 hours.

Some farmers use conventional 76 inch blades attached to cultivator frame to dig groundnut. A tractor-mounted digger-shaker-windrower is available in the Indian market. This equipment saves the loss of pods and reduces the cost of harvesting.

 Figure 6: Manual lifting of groundnut vines.