Effect of different cropping systems on manganese availability and transformations in soils
Loading...
Date
2020
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Punjab Agricultural University, Ludhiana-
Abstract
The present research study was conducted to investigate the transformation and depth-wise distribution
of manganese (Mn) in soils under different cropping systems viz. rice-wheat (RWCS), maize-wheat
(MWCS) and cotton-wheat (CWCS). A total of 150 surface (0-15 cm, 50 samples per cropping system)
and 18 profile (0-15, 15-30, 30-60, 60-90 cm, 6 per cropping system) samples were collected from three
different districts viz. Ludhiana (for RWCS), Ropar (for MWCS) and Mansa (for CWCS) in Punjab
(India). In addition, 150 plant leaf (flag leaf of rice, fully extended leaf of maize and a fully matured leaf
of cotton (50 each for crop) and 150 wheat leaf samples were collected from each soil sampling location.
Soils of MWCS had significantly higher mean DTPA-Mn and other fractions of variable solubility,
compared with the soils of other two investigated cropping systems. On the other hand, DTPA-Mn and
the concentration of different chemical fractions in soils under RWCS were significantly lower. The soils
under CWCS had significantly (p<0.05) higher soil pH, E.C. and CaCO3 as compared to other cropping
systems. The DTPA-Mn was lowest in the surface (0-15 cm) soil layer, and increased significantly with
depth in RWCS, in contrast to a decrease in soils under other two cropping systems. The different
fractions of variable solubility viz. WSEX-Mn, SpAD-Mn, OX-Mn, AFeOx-Mn, CFeOX-Mn, OM-Mn
and residual-Mn showed significant linear relationship (p<0.05) with soil organic C (SOC) and soils’
fine fraction (silt and clay). The Res-Mn fraction comprised the largest proportion (67-70%) while the
WSEX-Mn + SpAD-Mn fraction was the smallest Mn fraction in soils under different cropping systems.
Data pooled for different locations revealed that leaf Mn concentration in wheat leaves was highest in
crop sown in MWCS, followed by CWCS and the lowest in RWCS. Leaf Mn concentration showed a
significant relationship with DTPA-Mn and different Mn fractions. Foliar application of Mn significantly
influenced the wheat grain yield, Mn uptake and Mn use efficiency in wheat grown in different cropping
systems. A significant response of foliar application of Mn at different growth stages (vegetative as well
as ear initiation stage) was observed in all the three cropping systems. A quadratic response of relative
grain yield to DTPA-Mn after harvest of wheat revealed that 90% of the maximum yield was achieved
with foliar Mn application at 2.98, 3.69 and 3.82 mg DTPA-Mn kg-1 soil for RWCS, MWCS and CWCS,
respectively. Soil and foliar application of MnSO4 (25 and 50 ppm) either alone or conjointly with FYM
and PM (0.5%) in a pot experiment significantly increased the growth parameters and productivity of
wheat cultivars (PBW 725 and PDW 314) and Mn fractions in soil. Soil application of MnSO4 either
alone or conjointly with organic manures significantly increased the concentration of DTPA-Mn, totalMn,
WSEX-Mn, SpAd-Mn, Ox-Mn, AFeOX-Mn and CFeOX-Mn, OM-Mn and Res-Mn. The relative
preponderance of occurrence of different Mn fractions in soil followed an order: OM-Mn<SpAdMn<WSEX-Mn<Ox-Mn<
AFeOX-Mn<CFeOX-Mn<Res-Mn. Foliar application of Mn significantly
increased the number of effective tillers pot-1, grain ear-1, ear length, grain and straw yield pot-1 over soil
application, due to increased Mn concentration and uptake by grain and straw. The DTPA-Mn showed a
significant linear relationship with different Mn fractions, indicating that these fractions were in dynamic
equilibrium with each other and governs Mn availability in soil.