J.6 Broadcasting fertilizer in paddy fields, Tamil Nadu, India

Slide J.6 Broadcasting fertilizer in paddy fields, Tamil Nadu, India

In industrialized countries combined mechanized pest control and fertilizer spraying provides the necessary efficiency in the agricultural production process. In less developed parts of the world (slide J.6 shows rice farmers in Tamil Nadu, near Madurai) fertilizer is applied by manual labour.

In this particular slide (J.6), the fertilizer that is being applied had been mixed with neem cake prior to the broadcasting. Neem is a botanical product with insecticidal properties. The seeds of the neem tree are pressed to obtain the oil, and the left-over pulp (neem cake) has been tested in a number of field trials for their possible effect on the populations of Culex tritaeniorhynchus. Product standardization remains a problem without purification and characterization of the active ingredient Joint studies by the Centre for Research in Medical Entomology and the Tamil Nadu Agricultural University, both in Madurai, India, nevertheless demonstrated its effectiveness in irrigated rice fields in reducing vector populations at the very start of the irrigation cycle, but the vector density peak was only delayed and not eliminated, as the neem was broken down more rapidly than expected. As a beneficial side effect, there was a notable reduction of damage to the crop by the rice brown planthopper; on the negative side, there have been reports that neem has a detrimental impact on non-target organisms, including fish.

An attempt to combine neem with Azolla (see below) failed because the two turned out not to be compatible.