Efficient cropping systems and their energetics for sustainable irrigated tropical ecosystems

An experiment was conducted at Bheemarayanagudi, Karnataka, during 2010–11, 2011–12 and 2012–13 to find out efficient cropping systems and to know energetics of different cropping systems. Ten cropping systems, viz. sole Bt cotton (Gossypium spp.), Bt cotton–greengram [Vigna radiate (L.) Wilczek], Bt cotton–green-manure crop sun hemp (Crotalaria juncea (L.), Bt cotton–sesame (Sesamum indicum L.), maize (Zea mays L.)–chickpea (Cicer arietinum L.), sunflower (Helianthus annuus L.)–wheat [Triticum aestivum (L.) Emend. Fiori & Paol.], sunflower–chickpea, chilli (Capsicum annuum L.) + onion (Allium cepa L.) (1:2 row proportion), transplanted Bt cotton and rice–rice (Oryza sativa L.) as check were evaluated under irrigated condition to find out efficient cropping systems. The transplanted Bt cotton gave the maximum cotton-equivalent yield (2.73 t/ha) and was significantly superior to that of rice–rice (2.29 t/ha), while Bt cotton–greengram (2.53 t/ha), Bt cotton–sesame (2.61 t/ha), maize–chickpea (2.47 t/ha) and chilli + onion (2.41 t/ha) were at par with transplanted Bt cotton as well as rice– rice. All cropping systems gave significantly higher net returns over rice–rice cropping system ( 44,730/ha) except sunflower–wheat or chickpea; highest being with transplanted cotton ( 79,507/ha). All the systems were significantly superior to rice–rice (0.96) in benefit: cost ratio and maize–chickpea recorded the highest benefit: cost ratio (3.31). Energetics revealed different trend, wherein protein yields were higher with maize–chickpea (0.73 t/ha), while carbohydrate yield (6.32 t/ha) was higher with rice-rice. Among all the systems, the highest land-utilization index was observed with Bt cotton–sesame cropping system (76.7%).