Water for irrigation is a critical factor for plant growth in mountainous commercial forests. To solve this water deficiency one effective way would be application of super absorbent polymers (SAPs) that could be produced from wood processing residues. In this study two SAPs, bamboo fiber grafted with potassium acrylate (No.2) and bamboo fiber grafted with acryl amide (No.4), regenerated from bamboo sawdust were compared with commercial potassium polyacrylate (S) to determine the water-holding capacity (WHC) in three types of water (deionized water, tap water, and distilled water) and four fertilizer solutions (potassium sulfate, ammoni-um dihydrogen phosphate, compound fertilizer, and urea) with five gradient concentrations (0.5‰ ,1.0‰ , 2.0‰,4.0‰ and 8.0‰), as well as the WHC and nutrients protection in soils with or without fertilizers with same dosage (mass ratio of SAP to soil are 1:200). Also, effects of five dosages with a mass ratio of No.4 to soil being 1:100, 1:200, 1:400, 1:600, and 1:800, were designed to determine WHC and nutrient protection in soils with and without fertilizers. Results showed that the water absorption rate in the three types of water and four types of fertilizer solutions was highest with No.4 (P<0.05); whereas, S was significantly lower than the two SAPs (P<0.05). Water absorption rates for soils with and without fertilizers varied significantly (P<0.05) and followed the order of No.4>S>No.2. WHC was positively related to SAP dosage and greatly affected by the solution concentration from ionic fertilizers of potassium sulfate, ammonium dihydrogen phosphate, and compound fertilizer but not by urea, the non-ionic fertilizer. Also the highest WHC with SAP No.4, especially the treatment with highest dosage (mass ratio of SAP: soil = 1:100) resulted in the greatest loss of ammonium-N, nitrate-N, and potassium when the leaching water volume exceeded the WHC of the soil. In conclusion, SAP No.4 exhibited the greatest WHC and nutrient protection with a recommended dosage of 0.50% of the SAPs based on a dry soil mass (mass ratio of SAP: soil = 1:200), but should avoid fertilizing with maximum precipi-tation > 40 mm to minimize leaching.%水分是制约山区无灌溉条件商品林地植物生长的重要因子,保水剂的合理应用是解决植物水分供应的有效途径之一.大量的木材加工剩余物可再生为高效保水剂.以竹纤维接枝丙烯酸钾(2号)和竹纤维接枝丙烯酰胺(4号)2种毛竹锯屑再生型保水剂为研究对象,将商品保水剂聚丙烯酸钾(S)作为参照,通过模拟实验,对比他们在不同纯度的水中(去离子水、 蒸馏水和自来水),在不同的肥料溶液中(4种肥料,各5种质量分数配比)的吸水倍率;相同用量[m(保水剂):m(土壤)=1:200]的不同保水剂、 同一保水剂(4号)不同用量[m(保水剂):m(土壤)分别为1:100,1:200,1:400,1:600和1:800]对施肥和不施肥土壤的保肥、 保水能力的影响,旨在找到保水剂最佳施用量.结果表明:3种保水剂在不同纯度水以及不同质量分数的肥料溶液中的吸水倍率由高到低依次为4号、2号和S,且在同一纯度水中3种保水剂的吸水倍率均存在显著性差异(P<0.05);无论是否施肥与否,保水剂的保水能力依次为4号、S和2号,且4号、S、2号和对照(不加保水剂)之间差异显著(P<0.05).保水剂用量和土壤的持水能力呈正相关,保水效果受离子型的肥料(复合肥、 硫酸钾和磷酸二氢铵)配比影响较大,而受分子型肥料尿素的质量分数影响很小.当淋溶水量超过土壤持水能力时,保水能力最强的4号以及其用量最大的处理(1:100)养分(氮、钾)的淋出量最多(除磷以外).竹纤维接枝丙烯酰胺型保水剂保水保肥能力最强,考虑其经济成本,得出m(保水剂):m(土壤)=1:200(相当于土壤质量的0.5%)为最佳施用量;因4号保水剂1:200用量承受的最大降水上限为40 mm,应避免在大雨前施肥.
展开▼
