Non-labile phosphorus acquisition byBrachiaria

Abstract

Brachiaria are tolerant to low phosphorus (P) soils and may enhance P soil availability. The identification of mechanisms driving this effect is important. Our objective was to determine responses of palisade grass and ruzigrass to mineral oxide-bound P. Palisade grass (Brachiaria brizantha) and ruzigrass (Brachiaria ruziziensis) were grown in nutrient solution (NS), where P was supplied as goethite and amorphous aluminum-oxide (Al-oxide). Only half of each pot received P. Dry matter yields of Brachiaria species having oxide-P as the sole P source were similar to those grown with water-soluble P. Inorganic P was found in the NS after 7 days, and organic P at 14 days after plant emergence. The presence of dissolved organic carbon (DOC) indicates an intense and quick response of the root system to the treatments. Results indicate enzyme and/or organic acids (OAs) root exudation as a strategy of these plants to access soil sparingly soluble P forms.

Chemical evidence for the effect of Urochloa ruziziensis on glyphosate‐resistant soybeans

“…Brachiaria ruziziensis ) is a plant that can grow in various soils, from sandy to clayey, and it develops best in well‐drained soils with good fertility. The biomass production of these plants results in high levels of P and K present in soil . U. ruziziensis has faster decomposition and lower half‐life values than other plants and this in turn leads to nutrient recycling and higher maize yields …”

Chemical Characterization and Phytotoxic Effects of the Aerial Parts of Ruzigrass (Urochloa ruziziensis)

“…Brachiaria ruziziensis ), native to the Ruzi Valley in Zaire (Congo) and Burundi, is commonly known as ruzigrass or Congo grass . This species is widely distributed in tropical countries and grows in various types of soils, but it thrives in well‐drained soils with good fertility . Ruzigrass is cultivated for both animal feed and straw supplies for no‐tillage systems .…”

“…It is either intercropped with corn or grown as a single crop in rotation with soybeans because of its highly efficiency in producing biomass, which results in high levels of P and K recovery in soils and nutrient recycling . This species also stands out for its adaptability, aggressiveness, and drought‐resistance along with its vigorous growth and high tolerance to acidic soils . In addition, some studies have shown that this species reduces weed emergence in fields …”

“…[8,9] This species is widely distributed in tropical countries and grows in various types of soils, but it thrives in well-drained soils with good fertility. [7,10] Ruzigrass is cultivated for both animal feed [11] and straw supplies for no-tillage systems. [12] It has increasingly been used as a cover crop in many grain-producing areas of Brazil.…”

Can tropical grasses grown as cover crops improve soil phosphorus availability?

“…Phosphorus (P) uptake by cash crops has been observed to increase after growing cover crops, such as Lablab purpureus and Lupinus albus, due to release of P by the straw decomposition (Horst et al ., ) or due to an increase in soil P bioavailable pools (Calegari et al ., ). Recently, it has been shown that ruzi grass ( Urochloa ruziziensis ) and palisade grass ( Urochloa brizantha ) can mobilize and take up soil recalcitrant P bound to iron (Fe) and aluminium (Al) (Merlin et al ., ). Under no‐till, ruzi grass grown in the soya bean ( Glycine max ) off‐season enhances P cycling decreasing residual–P concentration in deeper soil layers (Almeida & Rosolem, ).…”