Stability of Soil Aggregates Treated with Distillery Slops or Blackstrap Molasses

Abstract

Data are presented on the effect, of the application of two levels of blackstrap molasses and of rum distillery slops on some soil physical conditions, and crop and nutrient yields of a poorly drained soil of New Jersey. A favorable lasting effect on soil aggregate stabilization with the application of a fourth of an acre-inch of distillery slops and blackstrap molasses was observed when these materials were applied to this soil. The effect persisted even altor the growth of four consecutive crops (snap beans, Sudan grass, wheat, and barley). The emergence of snap bean seedlings was favorably affected by the slops and molasses treatments, but the emergence of other crops was not influenced, hy these treatments. The uptake of P, K, and Ca by snap beans was increased by these treatments, as were the crop yields. Soil hydraulic-conductivity values also tended to increase with time in the check treatments. The values also tended to increase in the slops treatment, until the third crop, and slightly decreased after the removal of the fourth crop. Two possible explanations are offered for the decrease in hydraulic conductivity in contrast to the slight increase in aggregate stability with time. These are: First, aggregate stability was determined using 0.5- to 2-mm size aggregates separated from the soil by sieving. Since a breakdown of the macroaggregate was observed to occur after the last crop, the 0.5- to 2-mm sized aggregates which formed from these larger aggregates were quite stable. Further, since the smaller aggregates tend to create finer pores which retard water movement, the hydraulic conductivity values were reduced. The second possible explanation is that, since roots had been accumulating in the soil because of the growth of four crops, these probably plugged the macro- and micropores, thus sealing, to a certain extent, the channels that would have beenn available for the movement of water. The relatively high content of water-stable soil aggregates present, in the soil at the time of removal of the fourth crop is indicative of the resistance to decomposition of the organic cementing or bonding agents which are present in the slops and molasses, and are responsible for the formation of water-stable soil aggregates.