Compost addition and pre-planning soil moisture conditions alter soil nutrients, plant growth and nutrition, and the formation of mycorrhizas

Abstract

Composts are important materials to improve soil fertility. The release of nutrients from composts is affected by soil moisture. Recent work has shown that soil moisture conditions prior to planting can have a profound impact on soil nutrients, plant growth and nutrition, which is defined as the carry-over effect of soil moisture. However, the carry-over effect of soil moisture, especially in compost-amended soils has not been fully investigated. The present research aimed to investigate how soil moisture conditions prior to planting can alter available nutrients in the soil with and without compost addition. Arbuscular mycorrhizal fungi (AMF), which are abundant in the rhizosphere of most terrestrial plants, play an important role in nutrient uptake of plants. Thus, this study also investigated whether the pre-planting moisture conditions and compost addition affect the formation of mycorrhizas. A pot experiment was set up in a glasshouse-controlled condition over 88 days of the experiment. Soil moisture conditions were manipulated as wet (75% of field capacity (FC)), dry (25% FC) and cycle (one wet-dry cycle between 75% and 25% FC) treatments during pre-planting period. Soil moisture then was maintained constantly at 75% FC for all pots during planting period. Tomato and wheat were used as model plants to test potential carry-over effects of compost addition and pre-planting moisture conditions on plants. Overall, the results indicate a clear effect of soil moisture conditions prior to planting on plant growth and nutrition and mycorrhizal colonisation. The N content of plants was clearly associated with N availability in the soil. However, the P content of plants was not correlated with plant-available P in the soil. Tomato and wheat expressed superior growth in the pre-planting dry conditions where mycorrhizal colonisation of roots was also greatest, despite low available N nutrient in the soil at the time of planting. The study suggests that there is a possible synergistic effect of compost and mycorrhizal application in plant growth that needs to be further investigated.