| Samples of the top soil (0 to 20 cm beneath the ground) from cassava plantations in five demonstration
counties (Xingning, Wengyuan, Suixi, Kaiping, and Yunan) of CARS-12 Guangzhou Comprehensive Test Stationb ,
were selected to detect twelve indexes including pH value and organic content etc, to investigate the soil fertility of
cassava plantations in Guangdong. Results showed that pH value of the soil ranged from 4.5 to 6.0, showing strong
acidity. Organic matter content in Yunan and Wengyuan was at the average level (25.28 g/kg and 22.37 g/kg), while
that in Xingning, Suixi and Kaiping was relatively low (16 g/kg on average). With the average 75.95 mg/kg, the
nitrogen content in the cassava plantations investigated was low, while the available phosphorus content was relatively
high (>20 mg/kg). The available potassium content was not uniform, with the minimal of 85.61 mg/kg in Xingning and
the maximal of 252.66 mg/kg in Wengyuan. The exchangeable calcium content in soil was generally at the medium
level with an average of 409.41 mg/kg, while the content of exchangeable magnesium was low with an average of
39.50 mg/kg. There was no Cu and Fe deficiency in the cassava plantations investigated with an average of 0.66 mg/
kg and 122.86 mg/kg, respectively. The distribution of available Zn was not uniform, ranking as follows: Yunan >
Kaiping > Xingning > Suixi > Wengyuan. Except Xingning (62.29 mg/kg), the content of available Mn in other four
cassava plantations was at a low level. With an average content of 0.13 mg/kg, boron deficiency existed in all those five cassava plantations. Accordingly, reasonable fertilization by increasing the content of soil organic matter and paying
more attention to the applying of magnesium and boron fertilizer was suggested to improve the magnesium and boron
deficiency of cassava plantations in Guangdong. |
