Experimental Study on the Potential Use of Bundled Crop Straws as Subsurface Drainage Material in the Newly Reclaimed Coastal Land in Eastern China

Abstract

Initial land reclamation of the saline soils often requires higher drainage intensity for quick leaching of salts from the soil profile; however, drainage pipes placed at closer spacing may result in higher cost. Seeking an inexpensive degradable organic subsurface drainage material may satisfy such needs of initial drainage, low investment and a heathy soil environment. Crop straws are porous organic materials that have certain strength and endurance. In this research, we explored the potential of using bundled maize stalks and rice straws as subsurface drainage material in place of plastic pipes. Through an experimental study in large lysimeters that were filled with saline coastal soil and planted with maize, we examined the drainage performance of the two organic materials by comparing with the conventional plastic drainage pipes; soil moisture distribution, soil salinity changed with depth, and the crop information were monitored in the lysimeters during the maize growing period. The results showed that maize stalk drainage and the rice straw drainage were significantly (p < 0.05) more efficient in removing salt and water from the crop root zone than the plastic drainage pipes; they excelled in drainage rate, leaching fraction, and lowering water table; and their efficient drainage processes lowered salt stress in the crop root zone and resulted in a slightly higher level of biomass. The experimental results suggest that crop straws may be used as a good organic substitute for the plastic drainage pipes in the initial stage land reclamation of the saline coastal soils.

Influence of Straw Amendment on Soil Physicochemical Properties and Crop Yield on a Consecutive Mollisol Slope in Northeastern China

“…Monthly SM was also generally higher under SA than under NSA at the back of the slope, in both 2015 and 2016. This is most likely because SA increases infiltration and reduces evaporation [34], and infiltration and subsurface runoff increase with an increase in straw amendment [18,19]. However, ST usually increases with decreasing SM levels [12,21], which is not in agreement with our results, possibly because straw amendment decreases soil bulk density, increases infiltration and decreases heat capacity [35].…”

“…Therefore, our results suggest that ST and SM are not consistently affected by SA in top slope positions (relative flat). This was mainly due to the fact that the available water capacity and hydraulic conductivity of saturated soil typically increased with straw amendment [33], and straw amendment increased infiltration and the slope facilitated water movement towards the bottom [11,18,19,34]. The different results between 2015 and 2016 may have also been caused by variations in precipitation and the history of residue return (one year vs. two years) between 2015 and 2016, and may also be influenced by straw burial because it was difficult to evenly distribute the straw amendment using a tractor.…”

“…Daily SM at the bottom of the slope was lower under SA than under NSA (both before and after precipitation), and monthly SM at the bottom of the slope was generally lower under SA than under NSA, in both 2015 and 2016. This may be due to the fact that over time, soil amendment increases water infiltration and subsurface runoff at the bottom, especially as residue return increases annually [19,34]. Generally, the high SM at the bottom under both SA and NSA was not the factor that limited nutrient cycling and crop growth.…”

“…Effects of SA on the dynamics of soil water, runoff, infiltration, soil temperature, nutrients and soil water use and productivity are contradictory because of soil characteristics, climate and crop and soil management practices which vary enormously [9,[12][13][14]. Generally, residue incorporation reduces surface runoff, increases SM, crop transpiration and WUE (crop water use efficiency), and decreases ST; the extent to which this happens is mainly determined by the growth stage and the amount of residue returned to the soil [9,[16][17][18][19]. Furthermore, intensified straw application significantly reduces evapotranspiration at the grain-filling to the maturity stages, and significantly increases surface SM at the grain-filling stage and considerably improves rainfall-use efficiency (RUE) during the whole growth period [20].…”

Evaluating the Sustainable Use of Saline Water Irrigation on Soil Water-Salt Content and Grain Yield under Subsurface Drainage Condition

“…Similar studies by Bahceci et al and Lu et al suggested that the EC e within the root zone would reach a relative high level with the increase of IWS [1,53]. The proper depth of subsurface drainage changes with soil properties, soil salinity, and irrigation water salinity [54,55]. Using SALTMOD, Srinivasulu et al and Ghumman reported that it is not necessary to bury the subsurface pipe to a great depth, when the SDD > 1.4 m, the control of soil water-salt by subsurface drainage would not be meaningful [17].…”