Abstract:
In Eswatini, the production of castor bean is relatively low. This suggests that Emaswati have
limited information on the production of castor bean. Most farmers know castor as a wild weed
crop of less importance because of its low oil content compared to other agricultural oil crops.
Therefore, this study had the objective of sensitizing farmers about the importance of castor bean
and the recommended phosphorus and nitrogen fertiliser rates which are requisite towards
achieving higher yields and especially higher oil content. A field experiment was conducted at
the Crop Production Department experimental farm during the 2018/2019 cropping season. A
randomized complete block design (RCBD) was used in the experiment. There were six
treatment combinations ((1) Control, (2) 50 kg/ha LAN, (3) 100 kg/ha LAN, (4) Control, (5) 25
kg/ha P2O5 and (6) 50 kg/ha P2O5). Results showed that nitrogen fertiliser applied at 100 kg/ha
had the highest seed yield of 64.5 kg/ha and the lowest was 57.9 kg/ha at 50 kg/ha. However the
control of phosphorus had yield of 65.3 kg/ha. Also the results showed that application of
phosphorus at 25 kg/ha and 50 kg/ha recorded the lowest yield of 50 and 48 kg/ha respectively.
There was no significant difference in the seed yield between the treatments. Nitrogen applied at
100 kg/ha had the highest oil content of 1.6% compared to all the other treatments. The second
highest oil content recorded was 1% of 25 kg/ha of phosphorus fertiliser and the lowest recorded
was 0.6% from the control of nitrogen fertiliser. Number of fruits per plant was insignificant and
negatively correlated to oil content. The coefficient determination (R2) was 13.76%. This shows
a negligible contribution of the number of fruits per plant to oil content. The correlation
coefficient oil percentage content to yield was not significantly different and it showed a very
low coefficient determination (R2) of 10.50%. The oil content to seed yield contributed only
10.50 %, which indicates a very low contribution. It is concluded that application of nitrogen
fertiliser source LAN produced higher seed yield of (60.9 kg/ha) compared to application of
phosphorus fertiliser source P2O5 (54.4 kg/ha), although it was not significant. Application of
nitrogen fertiliser source LAN resulted to higher oil content of (1.03%) than application of
phosphorus with (0.93%) oil content. It is recommended that 100 kg/ha of LAN should be used
because it gave a high seed yield and oil content.
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