Heat accumulation and soil properties as affected by transparent plastic mulch in Blackgram (Vigna mungo) doubled cropped with Groundnut (Arachis hypogaea) in sequence under rainfed conditions in Tamil Nadu, India

Though plastic film mulch technology has been used widely to increase crop productivity in dryland farming, the economical as well as environmental costs associated with plastic mulches is the major factor limiting the wider adoption of this technology. With the objective of reducing the cost of plastic films by growing more than one crop prior to its disposal, experiments were conducted over 3 years (2012-15) during South West monsoon (SWM) and North East monsoon season (NEM) with four treatments, T1- Transparent plastic mulch maintained for two crops (TPM I), T2- Transparent plastic mulch laid new for each crop(TPM II), T3- Non mulched beds maintained for two crops (NM I) and T4 - Non mulched new beds for each crop (NM II). The crops sown were Blackgram (Vigna mungo) in the first season (SWM) and Groundnut (Arachis hypogaea) in the second season (NEM). Results indicated that soil temperatures appeared highest under transparent mulch in different phenophases of both blackgram and groundnut from sowing to harvest. The mulch film was physically sound even upto the harvest of the second crop (Groundnut) in each year of the study. The light transmission through the transparent mulch maintained for two seasons (TPM I) was also not relatively reduced which has been evidently seen in the soil temperature observed. Both air Degree −Days (DD) and soil Degree -Days (DD) varied between mulched and non- mulched treatments at all the phenophases of observation. The physical properties such as rate of water loss/day, hydraulic conductivity, soil bulk density and percentage of pore space of the soil were also influenced by transparent plastic mulch. Transparent mulch, either newly laid or maintained for two seasons, had an impact on yields of both blackgram and groundnut. As a result the net return was highest with the transparent plastic mulch maintained for both the crops. These results suggest that double-cropping of transparent plastic mulches can be done without loss of crop yield and provide significant savings in cost of land preparation, materials and laying cost, labour and disposal costs.