In sub-Saharan Africa (SSA), rice production from smallholder farms is challenged because of a lack fertilizer inputs and nutrient-poor soils. Therefore, improving nutrient efficiency particularly important for increasing both use yield. This review discusses how to improve the return input in terms agronomic N (AEN), that is, increase grain yield per kg applied N, SSA. The AEN values we summarized here revealed large spatial variations even within small areas certain gap between...

Visible and near-infrared (Vis-NIR) diffuse reflectance spectroscopy with partial least squares (PLS) regression is a quick, cost-effective, promising technology for predicting soil properties. The advantage of PLS that all available wavebands can be incorporated in the model, while earlier studies indicate models include redundant wavelengths, selecting specific refine analyses. This study evaluated performance waveband selection using Vis-NIR spectra to estimate total carbon (TC) nitrogen...

Phosphorus (P) deficiency is a major constraint for rice production in the tropics. Field-specific P management key resource-limited farmers to increase yields with minimal inputs. We used soil fractionation analysis identify relevant factors controlling uptake and responses fertilization of flooded highly weathered soils. Phytometric pot-based experiments modified Hedley were repeated soils from extensive regions geographically adjacent fields Madagascar. Large field-to-field variations...

As a laboratory proximal sensing technique, the capability of visible and near-infrared (Vis-NIR) diffused reflectance spectroscopy with partial least squares (PLS) regression to determine soil properties has previously been demonstrated. However, evaluation phosphorus (P) content—a major nutrient constraint for crop production in tropics—is still challenging task. PLS waveband selection can improve predictive ability calibration model, genetic algorithm (GA) widely applied as suitable...

Abstract Irrigated rice is less prone generally to phosphorus (P) deficiency than rainfed because redox reactions release P upon soil flooding. It not known whether that also true in highly weathered soils of Madagascar where the combination high Fe and low input may impede significant P. Soils flag leaf samples were collected 2010 38 irrigated 46 fields belonging private farmers. A critical content was derived from a P‐dosed pot trial study with three soils, results suggested 2.4 g P/kg as...

To optimize the nutrient management of upland rice production on tropical ferralsols, a greenhouse experiment was established using multi-nutrient omission approach. A reciprocal soil origin-rice cultivar transplant also conducted to better understand relative contributions origin and in limitation. We tested deficiency seven major secondary nutrients [nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), silicon (Si)] solution six micronutrients (B, Mn, Cu,...

Abstract Plant growth experiments were conducted to reveal the mechanism by which organic matter (OM) and soil flooding enhance phosphorus (P) bioavailability for rice. It was postulated that reductive dissolution of iron‐(III) [Fe(III)] oxyhydroxides in releases occluded phosphate ions (PO 4 ), i.e. , PO is not isotopically exchangeable original prior flooding. Rice grown P‐deficient treated with factorial combinations addition mineral P (0, 50 mg kg −1 OM ≈ 20.5 g as cattle manure +/– rice...

Soil color has been conventionally measured using a Munsell soil chart. Recently launched colorimeters can also measure the of an object at reasonable cost. This study was undertaken to evaluate what extent such low-cost (< 500 USD) be useful for analysis in laboratory as compared with conventional (> 3000 and chart (about 200 USD). Sixty two air-dried samples collected from rice fields Madagascar were subjected pretreatments homogenization (2-mm sieving or additional hand-grinding)...

Efficient phosphorus (P) fertilizer management is highly required for resource-limited farmers to achieve higher yields in typical P-deficient farmlands sub-Saharan Africa. Although soil P retention has been conventionally used estimate the possible responses applied soils, its applicability not clearly confirmed at field level. In this study, of predict response rice plants application was investigated using pot experiments with soils collected from various locations (N = 62) and on-farm...

Abstract Soil flooding increases phosphorus (P) availability due to reductive dissolution of P‐bearing Fe(III) minerals. It is, however, unclear whether such processes also act in P‐deficient soils the tropics that have large Fe/P ratios (dithionite‐ and oxalate‐extractable P Fe). The objective was identify extent release induced by soil characteristics involved. Six topsoils (0.4–5% Fe) from rice fields Madagascar were incubated aerobically anaerobically for 66 days amended with factorial...

Laboratory visible and near-infrared (Vis-NIR) spectroscopy with partial least squares (PLS) regression can be used to determine the soil carbon (C) content, waveband selection procedures refine predictive ability. However, individually selected wavebands are not always same depending on location, scale, approach. To simplify variable issue, some methods for selecting wavelength regions instead of individual have been proposed. In this study, we explore relevant predicting total (TC) content...

Iron (Fe) toxicity is a major constraint to rice yields in much of the world due greater solubility reduced ferrous Fe paddy soils compared with ferric aerobic and resulting excess uptake into plants. There genotypic variation tolerance Oryza gene pools, but so far only weak-effect alleles have been identified, largely because multiple critical physiological processes determine tolerance. Most past research has done nutrient solution screens at seedling stage, not under field conditions over...

Iron (Fe) toxicity is a widespread nutritional disorder in lowland rice causing growth retardation and leaf symptoms referred to as bronzing. It partly caused by an imbalance of nutrients other than Fe supply these known mitigate the toxicity. But physiological molecular mechanisms involved are unknown. We investigated effect magnesium (Mg) on tolerance field study Central Highlands Madagascar hydroponic experiments with excess (300 mg L-1). An RNA-seq analysis was conducted experiment...

Abstract Addition of organic matter ( OM ) to flooded soils stimulates reductive dissolution Fe( III minerals, thereby mobilizing associated phosphate (P). Hence, management has the potential overcome P deficiency. This study assessed if applications increases soil or mineral fertilizer availability rice under anaerobic (flooded) condition and that effect is different relative in aerobic (nonflooded) soils. Rice was grown P‐deficient treated with combinations addition (0, 26 mg P/kg), ~9 g...

Farmyard manure (FYM) – mixtures of animal droppings, crop residues, and fodder that are piled nearby homesteads is a major nutrient source for smallholder farmers in Sub-Saharan Africa. However, its application effect has not been fully understood on typical P-deficient soils tropics particular under anaerobic conditions. This study assessed the FYM irrigated rice relation to soil properties oxalate-extractable P (POx), pH, total C (TotC) important indicators deficiency region. The first...

Quantification of nutrient concentrations in rice grain is essential for evaluating uptake, use efficiency, and balance to develop fertilizer recommendation guidelines. Accurate estimation without relying on plant laboratory analysis needed sub-Saharan Africa (SSA), where farmers do not generally have access laboratories.The objectives are 1) examine if the macro- (N, P, K, Ca, Mg, S) micronutrients (Fe, Mn, B, Cu) can be estimated using agro-ecological zones (AEZ), production systems, soil...

Localized micro-dose fertilization near the seed or root zone can maximize returns from minimal fertilizer inputs. In transplanted rice production systems, two opportunities exist for implementing localized fertilization: Micro-dosing nursery bed at sowing and dipping seedling roots transplanting. Previous studies have focused on individual effects of these management options, whereas none identified how a combination techniques affect yields use efficiencies. Herein, we examined...

Phosphorus (P) deficiency is a major yield constraint for lowland rice production in the tropics. As P-fertilizer resources are finite, alternative fertilizer management needed sustainable production. We examined whether farmyard manure (FYM), nutrient source smallholder farms, can overcome issue typical P-deficient lowlands central highlands of Madagascar. A multi-location trial sites varying altitude and soil P availability, clarified that effect both FYM mineral application on grain...

Abstract Crop establishment is one of the major rice production operations that strongly affects production, productivity, and environmental impacts. This research introduced a new technology provided scientific evidence for benefits mechanized wet direct seeding (mDSR) as compared with other crop practices commonly applied by farmers seeded in Mekong River Delta Vietnam, such line using drum-seeder (dDSR) broadcast (bDSR). The experiment was implemented across two consecutive cropping...