Lugo-Ospina A, Dao Thanh H, Van Kessel J A, Reeves J B
Animal Manure and By-Products Laboratory, BARC East, Beltsville, MD 20705, USA.
Environ Pollut. 2005 May;135(1):155-62. doi: 10.1016/j.envpol.2004.09.007.
Nutrients in animal manure are valuable inputs in agronomic crop production. Rapid and timely information about manure nutrient content are needed to minimize the risks of phosphorus (P) over-application and losses of dissolved P (DP) in runoff from fields treated with manure. We evaluated the suitability of a commercial hand-held reflectometer, a hydrometer, and an electrical conductivity (EC) meter for determining DP and total P (TP) in dairy manures. Bulk samples (n = 107) collected from farms across CT, MD, NY, PA, and VA were highly variable in total solids (TS) concentration, ranging from 11 to 213gL(-1), in suspensions' pH (6.3-9.2), and EC (6.2-53.3 dS m(-1)). Manure DP concentrations measured using the RQFlex reflectometer (RQFlex-DP(s)) were related to molybdate-reactive P (MRP(s)) concentrations as follows: RQFlex-DP(s) = 0.471 x MRP(s) + 1102 (r2 = 0.29). Inclusion of pH and squared-pH terms improved the prediction of manure DP from RQFlex results (r2 = 0.66). Excluding five outlier samples that had pH < or = 6.9 the coefficient of determination (r2) for the MRP(s) and RQFlex-DP(s) relationship was 0.83 for 95% of the samples. Manure TS were related to hydrometer specific gravity readings (r2 = 0.53) that were in turn related to TP (r2 = 0.34), but not to either RQFlex-DP or MRP. Relationships between suspensions' EC and DP or TP were non-significant. Therefore, the RQFlex method is the only viable option for on-site quick estimates of DP that can be made more robust when complemented with TS and pH measurements. The DP quick test can provide near real-time information on soluble manure nutrient content across a wide range of handling and storage conditions on dairy farms and quick estimates of potential soluble P losses in runoff following land applications of manure.
动物粪便中的养分是农作物生产中的宝贵投入。需要快速及时地了解粪便养分含量，以尽量减少磷（P）过量施用以及施用粪便的农田径流中溶解态磷（DP）流失的风险。我们评估了一种商用手持式反射仪、一种比重计和一种电导率（EC）仪用于测定奶牛粪便中DP和总磷（TP）的适用性。从康涅狄格州、马里兰州、纽约州、宾夕法尼亚州和弗吉尼亚州的农场采集的大量样本（n = 107），其总固体（TS）浓度、悬浮液pH值（6.3 - 9.2）和EC（6.2 - 53.3 dS m(-1)）变化很大。使用RQFlex反射仪测量的粪便DP浓度（RQFlex-DP(s)）与钼酸盐反应性磷（MRP(s)）浓度的关系如下：RQFlex-DP(s) = 0.471×MRP(s) + 1102（r2 = 0.29）。纳入pH和pH平方项可改善根据RQFlex结果对粪便DP的预测（r2 = 0.66）。排除pH≤6.9的5个异常样本后，95%样本的MRP(s)与RQFlex-DP(s)关系的决定系数（r2）为0.83。粪便TS与比重计比重读数相关（r2 = 0.53），而比重读数又与TP相关（r2 = 0.34），但与RQFlex-DP或MRP均无关。悬浮液EC与DP或TP之间的关系不显著。因此，RQFlex方法是现场快速估算DP的唯一可行选择，当结合TS和pH测量时可使其更可靠。DP快速检测可提供关于奶牛场广泛处理和储存条件下粪便可溶性养分含量的近实时信息，以及土地施用粪便后径流中潜在可溶性P损失的快速估算。
