Performance of Maize (Zea mays L.) intercropping systems in lowlands

Abstract

The study entitled “Performance of maize (Zea mays L.) intercropping systems in lowlands” was undertaken at the College of Agriculture, Vellayani during 2021-2023. The objective was to evaluate different maize based intercropping systems in the summer fallow of double cropped lowland rice field in terms of weed dynamics, biological efficiency and economics. The field experiment was carried out at the Integrated Farming System Research Station (IFSRS), KAU, Karamana from January to May 2023 in Randomized Block Design with 10 treatments and three replications. The treatments comprised of T1: maize + bush cowpea (1:2), T2: maize + green gram (1:2), T3: maize + black gram (1:2), T4: maize + fodder cowpea (1:2), T5: sole crop of maize, T6: sole crop of bush cowpea, T7: sole crop of green gram, T8: sole crop of black gram, T9: sole crop of fodder cowpea and T10: fallow. Maize (var. TNAU maize hybrid Co-6) was raised as main crop and bush cowpea (var. PGCP-6), green gram (var.TM 96-2), black gram (var. VBN-6) and fodder cowpea (var. Aiswarya) were raised as intercrops. Maize was raised as per the recommendations of TNAU (CPG, 2005) and the intercrops as per KAU Package of Practice Recommendations (KAU, 2016). The results revealed that intercropping had significant effect on the growth and yield of the main crop and intercrops. Growth attributes of maize viz. plant height, number of leaves per plant, leaf area per plant and leaf area index (LAI) showed significant variation with intercropping. The treatment T5 resulted in taller plants, highest number of leaves per plant, leaf area per plant and LAI and it was followed by T1. Seed weight per cob (63.02 g), grain yield (4566 kg ha-1) and stover yield (13122 kg ha-1) were also highest in T5, which was followed by T3. Growth and yield attributes of intercrops were significantly reduced under intercropping systems. Sole crop of bush cowpea (T6), green gram (T7) and black gram (T8) recorded greatest plant height, number of branches per plant, leaf area per plant and LAI. Yield attributes like number of pods per plant, grain yield and haulm yield were also higher in sole cropping system. The plant height, number of branches per plant, leaf area per plant, leaf area index, leaf stem ratio, green fodder yield and dry fodder yield were higher in the sole crop of fodder cowpea (T9). Intercropping with maize profoundly reduced the weed count, weed dry matter production (DMP) and NPK removal by weeds. The lowest weed count was recorded in T9 at 30 DAS. At 60 DAS, lowest weed count was recorded in T3 and T1. The highest weed count was recorded in T10, both at 30 and 60 DAS. Lowest weed DMP was recorded in T1, 30 and 60 DAS. The weed smothering efficiency of maize + bush cowpea system was the highest among the different intercrops at 30 and 60 DAS (41.46 % and 59.04 % respectively). The N removal by weeds was lowest in T1(1.15 kg ha-1), which was on par with T4 (1.54 kg ha-1) at 30 DAS. At 60 DAS the lowest N removal was recorded in T1 (5.58 kg ha-1). P removal by weeds was lowest in T1 (0.62 kg ha-1, 0.64 kg ha-1) which was on par with T3 (1.78 kg ha-1,1.85 kg ha-1) both 30 DAS and 60 DAS respectively. K removal by weeds was lowest in T1 at 30 DAS (0.92 kg ha-1) and 60 DAS (2.22 kg ha-1). All the crops recorded higher values of NPK uptake under sole cropping of main crop and intercrops. The dehydrogenase activity was the highest in the maize + bush cowpea (T1) (175.52 µg TPF g-1 soil d-1) system compared to the others. The highest amount of available N in the soil found after the experiment was in T8 (472.29 kg ha-1) which was on par with T7 (397.23 kg ha-1) and T9 (397.23 kg ha-1). The highest amount of available P was found in T9 (71.00 kg ha-1) while available K was higher in T8 (168.64 kg ha-1). Analysis of the competitive indices of the intercropping system revealed that the land equivalent ratio (LER), monetary advantage index (MAI) and maize equivalent yield (MEY) were highest in the maize + black gram system (T3). The highest relative crowding coefficient and positive aggressivity value of maize indicated the dominance and competitive nature of maize over intercrops. The maize + black gram (T3) intercropping system recorded the highest net income (₹ 102262 ha-1) and B:C ratio (2.15). From the present study, it is inferred that in summer fallows of double cropped lowland, maize + black gram (1:2) system was more suitable in terms of maize equivalent yield, land equivalent ratio, monetary advantage index, net income and benefit cost ratio. Based on weed dry matter production, weed smothering efficiency and nutrient removal by weeds, the maize + bush cowpea (1:2) system was the best.