We used, and present, robust methodologies to measure the shortwave (S) and longwave (L) spectral radiative properties (reflectivity (ρ), transmissivity (τ) and absorptivity (α)) of nine plastic films and quantified their effect, when used as mulches, on soil heat flux density (G), net radiation (R_n, above the films) and soil temperature (T_s2cm, 2-cm depth; T_s10cm, 10-cm depth) in comparison to a control (bare soil). During the daytime, all treatments increased G when compared to the control to a maximum of ~45%, except for a plastic film that had a high shortwave ρ (ρ_s) value (0.45). The films with the highest α_s and ρ_s values had the highest and lowest daytime R_n, respectively. As a general rule, films with high τ_s and α_L values caused the greatest increases in G, T_s2cm and T_s10cm. In contrast, a comparison of three black plastic films with similarly high α_s and different longwave properties showed that the film with the highest α_L value achieved the lowest G and T_s2cm, which was unexpected. The daytime heat-sharing ratio (G/H, where H is sensible heat flux on the upward-facing side of the mulch) ranged in value from 0.80 ± 0.47 (mulch with τ_s = 0.79 α_L = 0.39) to 0.26 ± 0.13 (mulch with α_s = 0.96 α_L = 0.94). The lowest total daily downwelling shortwave radiation (S_d) required for total daily G to become positive was 9.4 MJ m⁻² compared to 17.6 MJ m⁻² for the control, which shows the potential of plastic films for growing-season extension.

我们使用了目前可靠的方法来测量九个塑料薄膜的短波（S）和长波（L）光谱辐射特性（反射率（ρ），透射率（τ）和吸收率（α）），并量化了使用时的效果作为覆盖物，与对照（裸土）相比，土壤热通量密度（G），净辐射（R _n，薄膜上方）和土壤温度（T _s2cm，深度为2厘米；T _s10cm，深度为10厘米） ）。在白天，所有治疗均增加G当与对照相比为最大的〜45％，除了塑料薄膜具有高的短波ρ（ρ_小号）值（0.45）。具有最高的膜α_小号和ρ_小号值具有最高的和最低的白天- [R _Ñ分别。作为一般规则，具有高薄膜τ_小号和α_大号值引起了最大的增加ģ，Ť _s2cm和Ť _s10cm。相比之下，三种具有相似高αs_的黑色塑料薄膜的比较和不同长波性质表明具有最高的薄膜α_大号值达到的最低ģ和Ť _s2cm，这是出乎意料的。热共享白天比（g ^ / ħ，其中ħ是在覆盖物的向上面向的侧感热通量）的值的范围为0.80±0.47（覆盖与τ_小号 = 0.79 α_大号 = 0.39）至0.26±0.13 （覆盖与α_小号 = 0.96 α_大号 = 0.94）。每日总G所需的最低每日总下行流短波辐射（S _d）变为阳性的为9.4 MJ m ^-2，而对照的为17.6 MJ m ^-2，这表明塑料膜具有生长季节延长的潜力。