Effects of tillage, irrigation regimes and nitrogen rates on productivity of canola in a loamy sand soil
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
Extensive cultivation of rice-wheat cropping system has led to fall of ground water table in
Punjab. Thus, oilseed crops can be used as an alternative due to lower water requirement. A
field experiment was conducted at the research farm of the Department of Soil Science,
Punjab Agricultural University, Ludhiana, during rabi 2018-19 to study the individual and
combined effects of deep tillage, irrigation and nitrogen rates on yield and productivity of
canola (Brassica napus). The treatments included combinations of two tillage systems viz;
deep tillage (DT) and conventional tillage (CT), with four irrigation regimes viz; no irrigation
(I0), one irrigation (I1), two irrigations (I2) and three irrigations (I3) in main plots and four
nitrogen (N) rates viz; 0 (N0), 50 (N50), 75 (N75) and 100 (N100) kg ha-1 in sub plots with three
replications. Lower soil moisture content was recorded under DT as more soil moisture was
utilized by the crop in this treatment resulting in lower soil moisture storage. Soil penetration
resistance reduced under deep tillage. Maximum rooting depth (180 cm) was obtained with
irrigation and 100 kg N ha-1. Root density in upper 60 cm soil depth was higher in I2 followed
by I1 and I0 irrigation regimes whereas below 60 cm, it was higher under I0. Higher root
density was recorded under DT and N100 plots. Irrigation and N application significantly
increased plant height, relative leaf water content, dry matter accumulation (DMA) and SPAD
value at all growth stages however, tillage only affected DMA significantly. Yield attributes
improved under I2DTN100. Seed yield significantly increased under DT (9.6 %) and I2 (25 %
over I0) treatment. Seed yield recorded under N100 was 9.1 q ha-1 higher over N0. Water
productivity improved with DT and N100. Oil yield and N uptake significantly increased with
successive increments of N rate and irrigation frequency. Higher nitrogen rates at low
irrigation frequency resulted in yield similar to low nitrogen rates at higher irrigation
frequency. Yield produced under DT with one irrigation was equivalent to that produced
under CT with two irrigations, suggesting saving of irrigation water.