Smart forage selection could significantly improve soil health in the tropics

Abstract

The use of tropical grasslands to graze livestock is of high economic importance. Declining grassland soil health leads to reduced sustainability of livestock systems. There are high levels of phenotypic diversity amongst tropical forage grasses. We hypothesise that this variation could lead to significant differences in soil health and that selection of forage cultivars to improve soil health could improve the sustainability of livestock production. We measured and compared key soil health metrics (soil organic carbon (SOC) concentration and sugar / alkane composition, aggregate stability, friability, litter decomposition rates, microbial community composition) under four tropical forage varieties (Brachiaria hybrid cv Mulato (BhMulato), B. humidicola cv Tully (CIAT679; Bh679), B. humidicola cv CIAT16888 (Bh16888), and Panicum maximum CIAT 6962 (Pmax)) and a bare soil control, there was a significant difference in soil aggregate stability, friability and SOC concentration between the forage varieties with soil under Bh679 and Bh16888 tending to have greater aggregate stability, friability and SOC concentrations compared to the soil under BhMulato and Pmax. We identified significant spatial variation in soils under BhMulato and Pmax due to their tussock forming growth habit; when compared to soil from adjacent to the tussocks, soil from the gaps between tussocks had significantly reduced aggregate stability under both species, significantly reduced friability under Pmax and significantly reduced SOC under BhMulato. We found limited impact of forage variety on soil microbial community composition, litter decomposition rates or soil alkane and sugar concentrations.

Urochloa in Tropical Agroecosystems

“…Introduction of forage species is justified when it provides services to the agroecosystem (Foley et al, 2005;Cherr et al, 2006). These services may be related to nutrient supply, increased nutrient use efficiency (NUE), soil protection and health, weed suppression and/or to the enhancement of crop or companion crop production and yields; also, they should be suited to local socioeconomic context (Cherr et al, 2006;Horrocks et al, 2019;Paul et al, 2020). Some plant traits are linked to the provision of these services, such as adaptation to tropical environmental conditions, low soil fertility requirements, high biomass production capacity, biomass recalcitrance, efficient root morphology and exudation activity, to name a few (Cherr et al, 2006;Horrocks et al, 2019).…”

“…There is evident scientific interest in the agronomic characteristics of Urochloa species. The International Center for Tropical Agriculture (CIAT) maintains a germplasm bank of more than 600 accessions of Urochloa spp., which can be used in breeding programs (Keller-Grein et al, 1996) or investigated for desirable traits for soil health improvement (Horrocks et al, 2019). The interest on this genus is justified for the genetic variability found for tolerance to drought, flooding, nutritional limitation, soil acidity, and against several diseases.…”

Strategy for Adaptation of Forage Crops to Climate Change

“…Dalam adaptasi perubahan lingkungan, beberapa jenis rumput dilaporkan memiliki sifat toleran kekeringan diantaranya: Cenchrus ciliaris, Panicum antidotale, Cynodon dactilon, Panicum coloratum, Setaria sphacelata (Prawiradiputra et al 2012) (Horrocks et al 2019). Rumput benggala (Megathyrsus maximus) dan signal grass (Brachiaria decumbens) (Urochloa spp dapat ditanam untuk adaptasi lingkungan karena termasuk rumput tropis yang menekan nitrifikasi tanah, mengurangi kehilangan N, sehingga meningkatkan manfaat pemupukan N dengan pada rotasi tanam (Rocha et al 2019).…”

“…Sorgum manis adalah tanaman yang toleran kering karena sedikit membutuhkan air, hasil yang tinggi, serta kualitas gizi yang serupa dengan jagung (Huang et al 2020). Padang penggembalaan di daerah tropis yang ditanami Brachiaria humidicola mempunyai stabilitas agregat tanah, kerapuhan dan kandungan karbon organik tanah yang lebih baik dibanding Panicum maximum (Horrocks et al 2019). Ryegrass (C3) menunjukkan hasil yang tinggi meskipun Hybrid rice grain (C3) mampu menghasilkan hasil yang lebih tinggi pada CO 2 tinggi sehingga berpotensi untuk dikembangkan di masa depan (Kimball 2016).…”

Carbon contents and fine root production in tropical silvopastoral systems

“…Nearly three billion hectares of land dedicated to livestock production have already depleted a huge amount (about 30–50%) of organic C but pose a high potential for C sequestration through silvopastoral practices (Baumann et al, 2017; FAOSTAT, 2020; Horrocks et al, 2019; Lal, 2008; Smith et al, 2016). In Latin America, the pastureland area increased from 229 to 564 million hectares from 1850 to 2015, and over 50% is currently used for beef cattle ( Bos taurus ) grazing (Baumann et al, 2017; Houghton & Nassikas, 2017).…”