Cover and Nurse Crops in Sal (Shorea robusta) and Teak (Tectona grandis) Plantations at Dehra Dun

This bulletin describes a series of investigations done at the Forest Research Institute, Dehra Dun, on the growing of cover and nurse crops in sal (Shorea robusta) and teak (Tectona grandis) plantations. The investigtions were started to see whether the formation and establishment of sal and teak plantations on exhausted agricultural fields which constituted the estate when it was taken over could be improved and hastened by nurse and cover crops. The experiments lasted from 1927 to 1940. The general conclusions reached are:- 1. None of the species tried prove really efficient as nurse and cover crops for sal at Dehra Dun and it is doubtful whether any are worthwhile - with the possible exception of Leucaena glauca; 2. The following species were successfully raised with sal - Leucaena glauca,Tephrosia candida, Indigofera endecaphylla, Indigofera galegoides and Indigofera tinctoria but none proved successful with teak; 3. The only species that appeared to have any beneficial effect on the growth of sal was Leucaena glauco and even this was doubtful; 4. All species needed intensive weeding to get them established (and their introduction is therefore expensive); 5. Leucaena glauco, Tephrosia candida and Indigofera endecaphylla were all partly successful as weed suppressers, the first named being the most effective, but Leucaena glauco and Tephrosia candida had to be repeatedly cut back in order to prevent them from suppressing the sal in the first few years. But in the case of teak, the growth from stumps, overtopped the nurse crop, Leucaena glauco, very soon. Due to this, the growth of the latter became very irregular and thus was not able to keep down the weeds and grasses; 6. after being partly damaged by frost for the first few years Leucaena glauca, Indigofera endecaphylla and Indigofera galegoides were reasonably efficient as forest nurses for sal; 7.Tephrosia candida was too short-lived and Indigofera endecaphylla too small a plant to be really useful with sal at Dehra Dun. Tephrosia candida raised simultaneously with teak was definitely harmful to the latter; 8. Leucaena glauca can be pruned at almost any height and at any time of the year without adverse results; 9. Tephrosia candida should not be pruned in the later years of its comparatively short life as this merely accelerates its death. It should be pruned early in the year because of its susceptibility to frost damage; 10. Indigofera endecaphylla can be heavily thinned in its third and fourth years without adverse effects; 11. Indigofera galegoides should be pruned early in the year to avoid damage to the new shoots by frost; 12. Indigofera tinctoria apparently will not stand pruning at Dehra Dun; 13. that moisture content in soils from areas with Tephrosia candida as a cover crop in Teak plantations is more reduced than in soils from areas without Tephrosia candida; 14. organic carbon and organic nitrogen are increased in areas with Tephrosia candida used as cover crop with both sal and teak and pH is reduced but not significantly as compared to those in areas without Tephrosia candida; 15. The nitrogen contents seems to be increasing with time on afforestation; 16. nitrogen and nitrogen as nitrates definitely decrease with the increase of the depth of the soil from ground level; 17. Tephrosia candida should be sown 4 to 6 weeks before the break of the monsoon. This early sowing results in slightly better survival per cent and an increase in mean height growth of 95% in the first growing season as compared with sowings made at the break of the rains. Detailed daily meteorological observations were recorded throughout the period of the experiments.