Variation in Nutrient Utilization By Various Crops Grown in a Previously Heavily Manured Dark Brown Chernozemic Soil.

Continuous application of livestock manure on agricultural land can result in the excessive build-up of nutrients, which may lead to nutrient loss to the environment. In this greenhouse study, we examined the effectiveness of six 40-day cycles of four crops (Barley, Canola, Corn, Pea and a barley-pea rotation), grown under two moisture regimes (100% and 50% of soil field capacity), at removing nitrogen (N) and phosphorus (P) from a Dark Brown Chernozem that had received 180 Mg ha^-1 of beef cattle feedlot manure (wet wt.) annually for 38 years. Results show that for most of the crops, available N in the soil was lower for plants receiving full watering than those watered to 50% of field capacity. Soil available P decreased significantly after six growing cycles for almost all crops in both watering regimes while there was a decrease in soil total N for canola and corn only. Similarly, plant N uptake decreased after the six crop cycles in both watering regimes for all crops. The N uptake by barley, canola, corn, pea, barley-pea at the end of the 240 d were 489, 1120, 1420, 441 and 596 mg kg^-1 soil respectively. While the P uptake by barley, canola, corn, pea, barley-pea were 68, 142, 189, 42 and 76 mg kg^-1 soil respectively after 240 d growth cycle. These results indicate that growing crops continuously can be a useful management practice to reduce nutrient levels in heavily-manured soils.