覆盖材料和沟垄比对土壤水分和紫花苜蓿干草产量的影响

Effects of mulching materials and furrow-to-ridge ratios on soil moisture and alfalfa forage yield

为寻求半干旱黄土高原区种植紫花苜蓿的适宜覆盖材料和最佳沟垄比,采用完全随机设计布置大田试验,以传统平作为对照,研究不同垄覆盖材料(土壤结皮、生物可降解地膜和普通地膜)和不同沟垄比(沟宽:垄宽分别为60∶30、60∶45和60∶60,单位是cm)对土壤水分和紫花苜蓿干草产量等的影响。结果表明:通过对2012年和2013年紫花苜蓿生育期降雨量统计,2a平均值显示,无效降雨次数(53次)大于有效降雨次数(27次),无效降雨对总降雨量的贡献率(19%)小于有效降雨(81%)。就紫花苜蓿全生育期而言,与平作相比,SR_(30)、SR_(45)、SR_(60)、BMR_(30)、BMR_(45)、BMR_(60)、CMR_(30)、CMR_(45)和CMR_(60)(SR、BMR和CMR分别代表土垄、生物可降解膜垄和普通膜垄,下标分别表示垄宽为30、45cm和60cm)连续2a的平均根层(0—140 cm)土壤贮水量分别提高12.8、19.2、24.4、26.0、30.7、40.5、29.9、37.1 mm和47.7 mm。垄沟集雨种植第1年龄和第2年龄紫花苜蓿根层没有出现明显干层。与平作相比,SR_(30)、SR_(45)和SR_(60)的连续2a紫花苜蓿平均实际干草产量分别降低3%、8%和13%,WUE分别提高52%、58%和55%;BMR_(30)、BMR_(45)、BMR_(60)、CMR_(30)、CMR_(45)和CMR_(60)的连续2a紫花苜蓿平均实际干草产量分别提高14%、12%、7%、17%、19%和9%,WUE分别提高49%、62%、59%、51%、67%和56%。当紫花苜蓿生育期降雨量为380.7—427.6 mm和沟垄比为60 cm∶35—36 cm时,生物可降解膜垄和普通膜垄的紫花苜蓿实际干草产量达到最大值,为该地区垄沟集雨种植紫花苜蓿提供参考。

To determine the optimum furrow-to-ridge ratio and a suitable ridge-mulching material for alfalfa production in a ridge-furrow rainwater harvesting system in the semi-arid Loess Plateau, a field experiment with a randomized complete block design was conducted during the 2012 and 2013 alfalfa growing seasons. The experiment was designed to investigate the effects of different mulching materials （ manually compacted soil crust, biodegradable mulch film, and common plastic film） and furrow to ridge ratios （60：30, 60：45, and 60：60 [cm ：cm] ） on soil moisture and alfalfa forage yield, with traditional flat planting （TFP） as a control. The average number of ineffective rainfall events （53） was greater than that of effective rainfall events （27） over these two years, and the contribution rate （ 19% ） of the ineffective rainfall to annual rainfall was less than that （ 81% ） of the effective rainfall. Compared with TFP, increases in the soil water storage at depths of 0--140 cm were 12.8, 19.2, 24.4, 26.0, 30.7, 40.5, 29.9, 37.1, and 47.7 mm in SR30, SR4s, SR60, BMR3o, BMR45, BMR6o, CMR30, CMR45. and CMR60（ SR, BMR, and CMR were ridges with manually compacted soil, covered with bio- degradable mulch film, and covered with common plastic film, respectively, and subscripts 30, 45, and 60 refer to ridge widths （ cm）, all with 60 cm furrow width）, respectively. There was no distinctive dry soil layer found within the root zone among ridge-furrow rainwater harvesting treatments during 2 consecutive years. Compared with TFP, forage yields decreased by 3%, 8%, and 13% for SR3o, SR45＇ and SR6o, respectively, while water use efficiency （WUE） increased by 52%, 58%, and 55% over the two years in these ridge-furrow systems. Forage yields increased by 14%, 12%, 7%, 17%, 19%, and 9% for BMR3o, BMR45, BMR60, CMR3o, CMR45 and CMR60, respectively, while WUE increased by 49%, 62%, 59%, 51%, 67%, and 56% in these ridge-furrow systems in the same period. Optimum furrow width was 35--36 cm for BMR and CMR in the ridge-furrow rainwater harvesting system with 60 cm furrows for alfalfa production in this region that has an annual 380.7--427.6 mm rainfall. This information is useful for alfalfa production in ridge-furrow rainwater harvesting systems in this region.