Addition biochar to enhanced soil quality and sugar beet crop grown under water stress treatments in salt-affected soils

Biochar amendment as agro-management technique could play an important role in
growing crops for high profit, enhancing the availability of water and nutrients in the root
zone environment, and maintaining soil fertility. The present study aims to evaluate the
benefit effects of biochar applications on some soil properties and in mitigating the adverse
effects induced by drought on sugar beet plants grown in salt-affected soils. Therefore, field
experiment was carried out in Demo farm, Faculty of Agriculture, Fayoum University,
Fayoum, Egypt. Three deficit irrigation regimes (i.e. I100= 100%, I80= 80% and I60= 60% of
crop evapotranspiration (ETc) and three application rates of biochar (i.e. B0 = zero addition
(control), B10 =10 (t ha-1) and B20 = 20 (t ha-1) were applied. The experimental treatments were
arranged in a complete randomized block design split-split plot with three replicates. Sugar
beet seeds (Beta vulgaris L., Baraca) was planted in two successive winter seasons along two
years (2019/2020 and 2020/2021) in salt affected soils (ECe =10.94 dS/m). The obtained
results revealed that biochar amendment improved soil moisture retention characteristics.
Biochar addition by 20 t ha-1 caused significant reduction in soil bulk density, hydraulic
conductivity, soil ECe by 2.94, 16.04 and 12.49 % respectively. Meanwhile under high level
of biochar addition 20 (t ha-1), field capacity (FC), available water content (AW), cation
exchangeable capacity and organic matter content were significantly increased by 18.03,
31.10and 11.76% respectively compared with control. In addition sugar beet growth
parameters (root length, root diameter, leaves number, leaves area and dry matter) and
physiological attributes (relative water content,
membrane stability index and SPAD) were
significantly affected by the applied deficit water regimes and biochar application levels.
However, sugar roots yield (t ha-1) and biomass yield (t ha-1) were reduced by 11.67 and
15.01% at (I80) and by 33.78 and 33.22% at (I60), respectively, compared with full irrigation
treatment. However, harvest index (HI) and water productivity (WP) recorded their maximum
values 0.68 and 18.18 (kgm-3), respectively, under moderate irrigation regime (I80). Thus, the
application of biochar treatments could be efficiently used to produce high productivity of
sugar beet crop and reduce the hazardous effects induced by salinity and drought stresses on
both growth and yield of sugar beet crop. In addition, the use of irrigation regime (I80) in
combination with biochar application rate (B20) could found to be a favorable agro-
management strategy to save 20% of the applied irrigation water and slightly decrease in yield
of sugar beet crop (11.67%) under Fayoum conditions.