Long-term crop rotation effects on organic carbon, nitrogen and phosphorus in Haplustoll soil fractions

 Long-term crop rotation effects on organic carbon, nitrogen and phosphorus in Haplustoll soil fractions

Soil organic matter (SOM) or carbon (SOC) consists of a number of fractions (which can be separated by granulometric wet sieving) having different properties among them. Information on fraction nutrient distribution and long-term crop rotations is lacking for semiarid environments. The objective of this research was to study the agronomic effects on soil OC, N, and P factions. The humified OC was the largest and least variable fraction of the SOC. Soil under continuous mixed pasture had higher OC contents than under annually tilled treatments. Similarly, soil total nitrogen under the cropped treatments decreased from 1.7 g N kg^-1 in noncultivated soils (reference plots) to 1.0, 0.7 and 0.7 g N kg^-1 under mixed pasture, pasture-crop, and wheat-crop respectively, in the fine soil fraction. The reference plots also showed significantly lower levels of organic phosphorus (Po) in comparison to the other treatment (from 67.1 µg Po g^-1 to greater than 100 µg Po g^-1 in the fine fraction of the treatments and years). The noncultivated soil showed larger values of Po and inorganic P in the large-size granulometric fraction (0.1-2 mm) than in the soil fine fraction (0-01 mm). However, the rotation treatments had greater concentrations of P in the fine fraction. The Po from the coarse fraction appears to be the most labile and sensitive fraction to tillage and environmental conditions, and may be closely related to P availability.

Keywords semiarid soil fractionation, organic P, inorganic P, tillage systems

Rosell R.A., J.A. Galantini, L.G. Suñer. 2000. Long-term crop rotation effects on organic carbon, nitrogen and phosphorus in Haplustoll soil fractions. Arid Soil Research and Rehabilitation 14 (4) 309-316.

 

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The effects of crop rotations and fertilization on wheat productivity

 The effects of crop rotations and fertilization on wheat productivity in the Pampean semiarid region of Argentina. 2. Nutrient balance, yield and grain quality

Wheat (Triticum aestivum L.) in the semiarid region of Argentina has often been grown as a low-input crop. Rainfall scarcity and distribution are the main characteristics of the region. Consequently, knowledge of the effect of different management practices is the key to sustainable crop production. The objective of this work was to study the effect of 15 years of different wheat management practices on plant nutrition, dry matter production and grain yield and quality. The treatments were: continuous wheat (WW), wheat-grazing natural grasses (WG) and wheat-legume: [vetch (Vicia sativa L.) plus oat (Avena sativa L.) or Triticale (Triticum aestivum L.  Secale cereale L.)] (WL), with and without fertilizer (N  P) application. The WW and WL treatments involved annual tillage and a long fallow period (4-6 months) under stubble mulch, and WG involved annual alternate tillage and a short fallow (1 month). The experiment was started in 1975 and the data presented were obtained in 1989. Wheat yields were higher with the WW than with the WG rotation, but in both rotations fertilization was required to obtain better grain quality (protein content higher than 11 per cent). The wheat-legume rotation resulted in the highest yield, protein content, and better yield components. Fertilizer application did not increase dry matter production but improved nutrient uptake and grain quality. Yield component differences could be attributed to water availability due to different fallow length. The wheat-legume rotation seemed to be the best practice 

Galantini J.A., M.R. Landriscini, J.O. Iglesias, A.M. Miglierina, R.A. Rosell. 2000. The effects of crop rotations and fertilization on wheat productivity in the Pampean semiarid region of Argentina. 2. Nutrient balance, yield and grain quality. Soil & Tillage Research 53: 137-144.

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The effects of crop rotations and fertilization on wheat productivity

 The effects of crop rotations and fertilization on wheat productivity in the pampean semiarid region of Argentina. 1. Soil physical and chemical properties

Wheat in the semiarid region of Argentina has often been grown as a low-input crop. Rainfall scarcity and distribution are the main characteristics of this region. The knowledge of the combined effects of crop rotation and fertilization on soil physical and chemical properties are the key for a sustainable crop production. Soil properties for an Entic Haplustoll in the semiarid region of Argentina were evaluated, where different crop rotations were used for 15 years. Wheat-wheat (Triticum aestivum L.) (WW), wheat-grazing natural grasses (WG) and wheat-legume [vetch (Vicia sativa L.) plus oat (Avena sativa L.) or Triticale (Triticum aestivum L.  Secale cereale L.)] (WL) rotations with and without fertilizer (64 kg N and 16 kg P ha^-1) were studied. The annual wheat cropping system (WW) resulted in the lowest soil organic carbon (SOC) and total nitrogen (Nt) levels. Extractable phosphorus (Pext) values were sufficient for wheat growth with all treatments and decreased with depth. Fertilizer applications significantly increased the proportion of large pores (>8.81 mm) in the 0±0.07 m depth of the WW and WG system plots. A decrease in the proportion of medium size pores (0.19-8.81 mm) and in the water holding capacity was observed in the WG rotation plots. The fertilized treatments resulted in the following sequence of available water: WL > WW > WG. Bulk density was similar with all treatments for each depth, except with the fertilized WG treatment that had the lowest value in the 0-0.07 m depth. These results showed the positive influence of legume inclusion (WL) and alternate cattle grazing (WG) on SOC and Nt contents.

Miglierina A.M., J.O. Iglesias, M.R. Landriscini, J.A. Galantini, R.A. Rosell. 2000. The effects of crop rotations and fertilization on wheat productivity in the pampean semiarid region of Argentina. 1. Soil physical and chemical properties. Soil & Tillage Research 53: 129-135. 

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Nutrient accumulation, balance and partition patterns in different wheat production systems

 

Little research has been done on the accumulation of N, P, K, and S in wheat plants growing under different crop production systems in the Pampean Semiarid Region. Consequently, the effects of wheat-grazing (TP), wheat-wheat (TT), and wheat-clover (TL), with and without fertilizer, production systems on total aerial dry matter (TADM) and N, P, K, and S accumulation at different growth stages were studied. Nutrient plant concentration decreased with the length of the cycle. Phosphorus and sulfur adequate levels were observed along wheat growing season. N deficiencies were observed since booting wheat growth stage. Potassium concentration sharply dropped between 90-140 growing days. Nitrogen, P, K and S uptake (kg ha^-1) gradually increased reaching the highest value at booting. Legume in crop sequences gave highest wheat dry matter, nutrient uptake and grain yield. Fertilizer application increased TADM and grain yield only in TT and TL.

Galantini J.A., M.R. Landriscini, R.A. Rosell. 2000. Patrones de acumulación, balance y partición de nutrientes en diferentes sistemas de producción de trigo. Revista de Investigaciones Agropecuarias (RIA-INTA) 29 (2) 99-110.

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