Shape

The aspect of shape is important at the field level. It influences the time spent on each field in the case of mechanized farming systems. On irregular-shaped fields, the number of turns and the area that is not cultivated at the end of the bouts increase. This consumes time and money [28]. In Table 2.6, some figures are given to indicate the loss of time on irregular-shaped fields compared to regular-shaped ones [28].

In Fig. 2.10, the field shapes that are used in Table 2.6 are visualized. All examples have an area of 10 ha (25 acres).

As with dimensions, the shape is only important in mechanized agricultural systems. The shape of a field is not very important to the farmer in less-developed systems, who does all the work by hand.

Table 2.6. Effect of field shape on the time to cultivate 10 haa

Field Shapeb

Cultivation Time (Min ha)

Index

Square

56.6

100

Rectangle (2:1)

54.0

95

Rectangle (4:1)

52.4

93

Re-entrant side

59.1

104

Building plots

60.5

107

Obstacles in field

62.0

109

a See also Fig. 2.9. b See Fig. 2.10. Source: [28].

a See also Fig. 2.9. b See Fig. 2.10. Source: [28].

Figure 2.10. Field shapes (see Table 2.6 for cultivation times).

square 1:2 1:4 obstacles re-entrant building

Figure 2.10. Field shapes (see Table 2.6 for cultivation times).

The effect of an irregular shape decreases when the size of the field increases. The time that is lost remains the same, but the amount of yield increases, and therefore the efficiency rises.

In Fig. 2.9, the relation between size and shape is shown in the context of losses at the edges. The horizontal axis represents the ratio of the length to the width of a field. The various lines indicate the field size, ranging from 0.25 ha to 16 ha. The graph shows that, as the acreage increases, the losses decrease. It is also clear that the effect of shape decreases as the acreage increases. On small fields, the shape is more important than the size. On big fields, it's the other way around. The optimum is at a ratio of approximately 2.5.

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