Cover crops are usually planted between cash crops to protect the soil, take up residual soil nitrate, and release nitrogen (N) to subsequent crops. Following cover crop termination, residues may remain on the soil surface, where their decomposition is largely dependent on residue temperature and water potential (${\psi }_{\text{residue}}$). While it is possible to continuously measure residue temperature, continuous measurements of ${\psi }_{\text{residue}}$ are impractical. Thus, a practical model to estimate ${\psi }_{\text{residue}}$ would be useful for models of residue decomposition. To obtain data for a model of ${\psi }_{\text{residue}}$ for cereal rye (Secale cereale L.) and crimson clover (Trifolium incarnatum L.), we conducted studies that evaluated the effects of (1) residue stage of decomposition on water release curve; (2) relative humidity (RH) on ${\psi }_{\text{residue}}$; (3) soil moisture on residue gravimetric water content (${\theta }_g);\left(4\right)$ precipitation on ${\theta }_g$; and (5) diurnal changes in RH and temperature on ${\psi }_{\text{residue}}.$ Results showed that water release curves for cereal rye and crimson clover changed as decomposition progressed, and that parameters for these curves could be estimated from residue lignin content. Both types of residues rewetted at a similar rate when exposed to high RH, but when rewetted by rainfall, cereal rye required a lower amount of rainfall than crimson clover to reach maximum water content. Results of these studies were used to develop, calibrate, and validate a model of ${\psi }_{\text{residue}}$ that requires inputs of initial water and lignin contents of the residue as well as hourly values of relative humidity, air temperature, and precipitation. Comparison of observed vs. simulated data indicated the model simulates reasonably well the observed diurnal patterns of surface ${\psi }_{\text{residue}}$ with R²=0.84. Because this model requires a small set of parameters and input variables, its use may be more practical than that of more detailed models.

覆盖作物通常种植在经济作物之间，以保护土壤，吸收土壤中残留的硝酸盐，并将氮（N）释放给后续作物。覆盖作物终止后，残留物可能会留在土壤表面，它们的分解在很大程度上取决于残留物温度和水势（${\psi }_{\text{残留物}}$）。虽然可以连续测量残留温度，但可以连续测量${\psi }_{\text{残留物}}$是不切实际的。因此，一个实用的模型来估计${\psi }_{\text{残留物}}$对残差分解模型很有用。获取模型的数据${\psi }_{\text{残留物}}$对于谷物黑麦 ( Secale carbone L.) 和深红色三叶草 ( Trifolium incarnatum L.)，我们进行了评估 (1) 残留分解阶段对水释放曲线的影响的研究；(2) 相对湿度 (RH) on${\psi }_{\text{残留物}}$; (3)土壤水分对残渣重量含水量(${\theta }_G);\left(4\right)$ 降水 ${\theta }_G$; (5) RH 和温度的昼夜变化${\psi }_{\text{残留物}}.$结果表明，谷物黑麦和深红色三叶草的水分释放曲线随着分解的进行而发生变化，这些曲线的参数可以从残留的木质素含量中估算出来。当暴露于高 RH 时，两种类型的残留物以相似的速率再润湿，但是当被降雨再润湿时，谷物黑麦需要比深红色三叶草更少的降雨量才能达到最大含水量。这些研究的结果用于开发、校准和验证模型${\psi }_{\text{残留物}}$这需要输入残留物的初始水分和木质素含量，以及每小时的相对湿度、气温和降水值。观测数据与模拟数据的比较表明该模型相当好地模拟了观测到的地表昼夜模式${\psi }_{\text{残留物}}$R ² =0.84。因为这个模型需要一小组参数和输入变量，所以它的使用可能比更详细的模型更实用。