112 *Corresponding author e-mail: raghavendra4449@gmail.com System productivity and economics infuenced by residue and potassium management in maize (Zea mays)-wheat (Triticum aestivum) rotation RAGHAVENDRA M * , Y V SINGH, M C MEENA, T K DAS, S SEPAT and R K VERMA ICAR-Indian Agricultural Research Institute, New Delhi 110 012, India Received: 16 February 2019; Accepted: 29 August 2019 ABSTRACT A feld experiment was conducted during kharif and rabi 2014-2016 at ICAR-IARI, New Delhi to study the system productivity, economics and energetics of maize (Zea mays L.) and wheat (Triticum aestivum L.) as infuenced by crop residue (CR) and potassium (K) management under zero till maize-wheat system. The experiment was laid out in split plot design with four CR levels (0, 2, 4 and 6 t/ha) and fve K levels (0, 50%, 100%, 150% RDK [recommended dose of K] and 50% RDK+Potassium solubilizing bacteria, KSB). Results revealed that signifcantly higher system productivity, output energy, specifc energy and highest energy intensiveness, actual change in available K were found with 4.0-6.0 t/ha CR. Maximum B: C ratio in maize-wheat system was observed with No CR followed by 2.0-4.0 t/ha CR. Highest net energy returns, energy use-effciency, energy productivity and lowest input energy (351- 395%) in both crops were registered with No CR fb 2.0-4.0 t/ha CR. Among K management, 50% RDK+KSB was signifcantly superior over rest levels. The maximum system net returns, B:C ratio, output energy, net energy returns, energy use-effciency and energy productivity were found in 50% RDK+KSB and consumed only 0.34-0.35% higher input energy over no K in maize and wheat. Change in available K was more in 150% RDK fb 50% RDK+KSB and 100% RDK. Thus, a combination of 2.0-4.0 t/ha CR retention and 50% RDK along with seed inoculation with KSB improved system productivity, net returns and energetic parameters in zero tillage maize-wheat system, and brought positive change in available K and hence can be recommended for adaptation by the farmers. Key words: Available potassium, Conservation agriculture, Energetics, Indo-Gangetic Plains, Potassium solubilizing bacteria, Zero tillage Crop residue (CR) is considered as valuable natural resource for agro ecosystem stability (Raghavendra et al. 2020). India generates 84-141 million ton (mt) of total surplus CR every year, out of which cereals contribute 23% (MNRE 2009). About 75% of K-uptake by cereals can be retained in CR, making them valuable nutrient sources (Raghavendra et al. 2017). Farmers burn CR in open feld at Indo-Gangetic Plains (IGP) of India, which leads to emission of harmful gases and air pollutants into atmosphere with loss of plant nutrients (Raghavendra et al. 2018). To minimize this problem, recycling of nutrients through CR retention is one of the desirable options in IGP (Prasad 2005). Potassium (K) is the third macro-nutrient required by crop plants and plays a signifcant role in growth, development and provides resistance to biotic and abiotic stresses (Raghavendra et al. 2020). Average yield losses of maize and wheat in farmer’s felds due to K-omission were 700 and 715 kg/ha, respectively (Majumdar et al. 2012). This suggests that skipping application of K in these two cereals will cause variable yield and economic loss to farmers in the region and will affect overall cereal production of the country (Majumdar et al. 2012). Currently, no reserves of K-bearing minerals in India for production of commercial K-fertilizers and whole consumption of K-fertilizers imported, which involves huge amount of foreign exchange. This necessitates, to fnd an alternate K source that can meet plant’s K needs and maintain K status in soils for sustaining crop production. Applied inorganic K fertilizer gets bound with other minerals and only 1-2% available for crop uptake. Under such circumstances, biological extraction of K holds good promise. Potassium solubilizing microorganisms have potential to solubilise K minerals by excreting organic acids (Meena et al. 2015). However, the performance of KSB depends upon their establishment in soil niche and may vary with type of strain, crop management practices and test crops and thus needs to be investigated. Keeping this in view present experiment undertaken to study the system productivity and economics of maize (Zea mays L.)-wheat (Triticum aestivum L.) system under conservation agriculture based best management practices. MATERIALS AND METHODS The feld experiment was conducted during kharif Indian Journal of Agricultural Sciences 90(4): 784–9, April 2020/Article https://doi.org/10.56093/ijas.v90i4.102224