Preparation of carbon-based material with high water absorption capacity and its effect on the water retention characteristics of sandy soil

Biochar has the potential to provide a multitude of benefits when used in soil remediation and increasing soil organic matter enrichment.Nevertheless,the intricated,hydrophobic pores and groups weaken its water-holding capacity in dry,sandy soils in arid lands.In order to combat this issue,starch-carbon-based material(SB),sodium alginate-carbon-based material(SAB),and chitosan-carbon-based material(CB)have been successfully synthesized through the graft-polymerization of biochar(BC).A series of soil column simulations were used to scrutinize the microstructure of the carbon-based material and explore its water absorption properties and its effects on sandy soil water infiltration,water retention,and aggregation.The results indicated that SB,SAB,and CB achieved water maximum absorption rates of 155,188,and 172 g g^(−1),respectively.Considering their impact on sandy soils,SB,SAB,and CB lengthened infiltration times by 1920,3330,and 3880 min,respectively,whilst enhancing the water retention capabilities of the soil by 18%,25%,and 23%in comparison to solely adding BC.The utilization of these innovative materials notably encouraged the formation of sandy soil aggregates ranging from 2.0 to 0.25 mm,endowing the aggregates with enhanced structural stability.Findings from potting experiments suggested that all three carbonbased materials were conducive to the growth of soybean seeds.Thus,it is evident that the carbon-based materials have been fabricated with success,and they have great potential not only to significantly augment the water retention capacities and structural robustness of sandy soils in arid areas,but also to bolster the development of soil aggregates and crop growth.These materials possess significant application potential for enhancing the quality of sandy soils in arid and semi-arid regions.

Effects of Different Harvest Periods on Seed Quality of Alpinia oxyphylla Miq.

[Objectives] To clarify the appropriate harvest period of Alpinia oxyphylla Miq. seed and improve the quality of seeds. [Methods] In this experiment,the basic parameters and germination characteristics of A. oxyphylla Miq. seeds during different harvest periods were analyzed and compared. [Results] The results showed that the A. oxyphylla Miq. fruit picking period was closely related to the seed quality,and the seed maturity was highest 100 d after the flowering of A. oxyphylla Miq.,that is,the A. oxyphylla Miq. fruit skin turned from green to yellow( yellow-green),the peel had a small number of brown spots,it was spicy enough,the fruit dry/fresh weight ratio was greater than0. 34,the seed thousand kernel weight reached 11 g or more,and the dried seed moisture content was 13. 01%. Using the TTC method,the seed viability index was determined to be 85%,and in this case,it was the best time of harvesting seed. The water permeability of A. oxyphylla Miq. seed was poor,and the seed imbibition and water absorption time was long,about 72 h. The maximum water absorption rate was about23. 71% at the imbibition and water absorption stage,and it was inferred that the A. oxyphylla Miq. seeds were hard seeds. The germination time of A. oxyphylla Miq. seeds was long,the mature A. oxyphylla Miq. seeds began to germinate on the 12 th d,and the germination rate reached 75. 56% on the 50 th d. [Conclusions] This study determined the optimum harvest period of A. oxyphylla Miq. seeds,clarified the biological characteristics of slow seed water absorption and long germination cycle,and concluded that the seed coat was the main factor leading to slow seed water absorption and long seed germination cycle.

Effect of Substituting Plantation Species for Native Shrubs on the Water-holding Characteristics of the Forest Floor on the Eastern Tibetan Plateau

Although the forest floor plays important roles in water-holding and nutrient cycling, there is not enough knowledge of the functional changes of the forest floor resulting from changes in vegetation. To evaluate the effect on the hydrological properties of forest floor by the substitution of plantation species for native coppice, we selected four species substituting plantations and one native coppice （secondary native broad-leaved forest, dominated by Quercus liaotungensis and Corylus heterophylla var. sutchuenensis） （QC） as a comparison forest. The substituting plantations were Cercidiphyllum japonicum （Cj）, Pinus tabulaeformis （Pt）, Pinus armandi （Pa）, Larix kaempferi （Lk）. These were established in 1987 with a stocking density of approximately 2500 stem ha -1 . Thickness and the amount of floor in coniferous plantations were significantly higher compared to secondary native broad-leaved forest and pure broad- leaved plantation. The maximal water-holding capacity of the floor showed the same trend as thickness and amount of litter. Main contributors to the difference in hydrological characteristics in the plantations were the quantity of forest floor and the maximal water holding capacity per unit weight of the floor. The relationships between water absorption processes, water absorption rate and the immersion time for litter, fitted to logarithmic and exponential regressions, respectively. Water absorption processes differed significantly between the various plantations and different decomposition floor horizons. Water absorption characteristics were influenced by leaf structure in various tree species and the degree of decomposed litter. Our results showed that litter amount in coniferous plantations were significantly higher than in deciduous broad-leaved plantation. This suggests that a large amount of nutrients are held in the litter horizon, delaying return to the soil and utilization by plants. At the same time, maximal water-holding capacity of the forest floor in F [fermentation] and H [hummus] horizons was significantly higher than that in L [fresh litter] horizon. Therefore, improving litter transformation from L horizon to F and H horizons by promoting forest floor environment would be one of the best methods for plantation management.