Using woody organic matter amendments to increase water availability and jump‐start soil restoration of desertified grassland soils of Ningxia, China

Abstract

Solutions are urgently needed to address the continued degradation of agricultural soils worldwide, which has severely impacted the ability to grow crops and has led to increased irrigation demand from already rapidly depleting freshwater resources.This project evaluated a unique, previously untested, type of soil organic amendment, that is, coarse wood chips, for capturing and storing scarce precipitation and improving desertified, sandy soils. A field plot experiment was conducted in Ningxia, China, from 2011 through 2016, comparing unamended sandy soils with three coarse woody amendments, including (a) surface-applied mulch, (b) wood chips incorporated into the top 20 cm of soil, and 3) incorporated wood chips combined with a branch lattice shelter over the soil surface-all treatments replicated under both irrigated and nonirrigated conditions. Precipitation patterns and soil moisture content were compared between 2012 and 2015, and related soil physical and chemical properties were monitored continuously, as well as alfalfa yields in 2015 and 2016. Results indicated that amended soils maintained significantly higher soil water contents between rain events, decreased the number of days below the permanent wilting point, and improved soil properties and alfalfa growth. The combination treatment of wood chips and a branch shelter performed the best among treatments, exhibiting increases in average water storage 50% or more above controls. Unlike highly degradable soil amendments, the slow decomposition of the coarse wood chips resulted in continuous benefits for all 5 years. This use of coarse wood chips represents a timely new addition to the toolbox of soil amendments, providing a mechanism for immediate, long-lasting restoration of the world's degraded and desertified soils that will foster global food and water security.

New approaches: Use of assisted natural succession in revegetation of inhabited arid drylands as alternative to large-scale afforestation

“…Water storage capacity was increased by 50% when sandy soil was amended with wood chips (5%) and covered with branches. Nutrients from decomposition of the wood chips were found to increase the biomass production over at least five years compared to controls [12]. The method was therefore suggested as long-term treatment to restore degraded soils, and its suggested use in combination with other restoration measures is reviewed in below (6.1).…”

“…(1) Soil tillage (harrowing, ploughing)-module areas where soil is compacted [22,37] (2) organic matter (e.g., compost, wood chips, branches, straw) worked into soil, mulching of cover soil [12] (3) planting of shelterbelts [3] or twin greenbelts [13] for optimal windbreak, using native shrubs and trees, fences, ditches, water pools (4) creating maintenance paths, particularly in areas of assisted succession where initial irrigation is planned (5) depending on local seed bed optional dispersal of native plant seed transplanted from adjacent donor biotope [7] (6) inoculation with cyanobacteria, mosses or biocrust fragments [15,17,35] on most disturbed parts of the successional area (7) biocrust development will require regular irrigation during first months (8) in semi-arid areas of MAP > 300 mm, the belt trees are watered during planting and would typically not require further irrigation [6].…”

“…We review recent measures which are hoped to potentially make succession successful here. These include methods that were demonstrated to be successful in the restoration of soil for long-term agricultural use e.g., [11,12].…”

“…A method for revegetation of drylands that combines the active planting of twin greenbelts and the process of sheltered natural succession was suggested [13]. Besides this model of planted "renaturation compartments" and a similar shelterbelt system used in Northern China [3], we review methods of soil tillage, soil amendment [12] and the formation of "biocrusts" within only one year, done by inoculation of the surface soil with cyanobacteria, mosses or lichens [14][15][16][17] to identify how these methods can be applied, also in combination, in order to initiate and accelerate successional processes.…”

Historic Grazing Enhances Root-Foraging Plasticity and Assimilation But Not Absorbability For Nitrogen of Clonal Offspring in Leymus Chinensis

“…Using the Kjeldahl method, total concentrations of plant and soil N were measured (Wang et al 2018). The soil organic matter content was analyzed using dichromate oxidation (Li et al 2019b). In addition, available soil N soil was photometrically measured by a continuous ow analyser (SAN Plus, Skalar, Netherlands) from on-site KCl extractions using the fresh soil (Geng et al 2017).…”